#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include "cJSON.h"
#include "cst_agent.h"
#include "cst_perms.h"
#include "cst_tools.h"
#include "cst_util.h"
#include "os_compat.h"
#include "sashidown.h"

#include <locale.h>
#include <pthread.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wchar.h>
#include <ctype.h>
#include <wctype.h>

#ifdef _WIN32
#include <io.h>
#include <windows.h>
#else
#include <langinfo.h>
#include <strings.h>
#include <unistd.h>
#endif

static int g_nocolor; /* NO_COLOR */
static int g_ascii;   /* non-UTF-8 locale or CST_ASCII=1 */
static int g_utf8 = 1; /* locale can show non-ASCII text */
#define HAS_COLOR() (!g_nocolor && has_colors())

/* Curses: ncursesw on Unix, PDCurses (wide) on Windows. */
#if defined(CST_USE_PDCURSES) || defined(_WIN32)
#ifndef PDC_WIDE
#define PDC_WIDE 1
#endif
#ifndef NCURSES_MOUSE_VERSION
#define NCURSES_MOUSE_VERSION 2
#endif
#include <curses.h>
#ifndef BUTTON4_PRESSED
#define BUTTON4_PRESSED 0
#endif
#ifndef BUTTON5_PRESSED
#define BUTTON5_PRESSED 0
#endif
#ifndef KEY_RESIZE
#define KEY_RESIZE 0632
#endif
/* MinGW often lacks wcwidth; simple East-Asian / ASCII heuristic. */
static int cst_wcwidth(wchar_t wc) {
  if (wc == 0)
    return 0;
  if (wc < 32 || (wc >= 0x7f && wc < 0xa0))
    return -1;
  if (wc >= 0x1100 &&
      (wc <= 0x115f || wc == 0x2329 || wc == 0x232a ||
       (wc >= 0x2e80 && wc <= 0xa4cf && wc != 0x303f) ||
       (wc >= 0xac00 && wc <= 0xd7a3) || (wc >= 0xf900 && wc <= 0xfaff) ||
       (wc >= 0xfe10 && wc <= 0xfe19) || (wc >= 0xfe30 && wc <= 0xfe6f) ||
       (wc >= 0xff00 && wc <= 0xff60) || (wc >= 0xffe0 && wc <= 0xffe6) ||
       (wc >= 0x20000 && wc <= 0x2fffd) || (wc >= 0x30000 && wc <= 0x3fffd)))
    return 2;
  return 1;
}
#define wcwidth cst_wcwidth
#else
#include <ncurses.h>
#endif

#ifdef _WIN32
static void cst_usleep(unsigned usec) {
  Sleep((usec + 999) / 1000);
}
static int cst_clock_gettime_mono(struct timespec *ts) {
  static LARGE_INTEGER freq;
  static int init;
  LARGE_INTEGER c;
  if (!init) {
    QueryPerformanceFrequency(&freq);
    init = 1;
  }
  QueryPerformanceCounter(&c);
  ts->tv_sec = (time_t)(c.QuadPart / freq.QuadPart);
  ts->tv_nsec =
      (long)(((c.QuadPart % freq.QuadPart) * 1000000000ULL) / freq.QuadPart);
  return 0;
}
#define usleep(us) cst_usleep((unsigned)(us))
#define clock_gettime(clk, ts) cst_clock_gettime_mono(ts)
#ifndef CLOCK_MONOTONIC
#define CLOCK_MONOTONIC 1
#endif
#endif

/*
 * OpenCode-inspired C ncurses/PDCurses TUI:
 * structured transcript blocks, thinking/tool cards, permissions, cancel.
 */

#define INPUT_CAP 32768
#define SCROLL_SPEED 3
#define REPLAY_MSGS 30
#define MD_INIT (64 * 1024)
#define ANSI_INIT (64 * 1024)
#define TOOL_PREVIEW_LINES 3
#define DIFF_FOLD_LINES 40
#define BLOCKS_INIT 64
#define MAX_RENDER_LINES 65536
#define PROMPT_HIST_CAP 50
#define QUEUE_CAP 3
#define INPUT_MAX_ROWS 8
#define COMP_MAX 8
#define TODO_PANEL_MAX 6
#define ASK_OPTS_MAX 9
/* Bracketed paste markers, bound with define_key() above KEY_MAX. */
#define KEY_PASTE_BEGIN (KEY_MAX + 1)
#define KEY_PASTE_END (KEY_MAX + 2)

/* Color pair indices */
enum {
  CP_HEADER = 1,
  CP_STATUS,
  CP_INPUT,
  CP_PRIMARY,   /* user / accents */
  CP_ASSIST,    /* cyan assistant */
  CP_MUTED,
  CP_SUCCESS,
  CP_ERROR,
  CP_TOOL,
  CP_PANEL,     /* transcript bg */
  CP_SGR_GREEN,
  CP_SGR_YELLOW,
  CP_SGR_CYAN,
  CP_SGR_MAGENTA,
  /* OpenCode-style structured diff (bg distinguishes add/del/context) */
  CP_DIFF_ADD,
  CP_DIFF_DEL,
  CP_DIFF_CTX
};

typedef enum {
  BLK_USER = 0,
  BLK_ASSISTANT,
  BLK_THINK,
  BLK_TOOL,
  BLK_STATUS,
  BLK_SYSTEM
} block_kind_t;

typedef struct {
  block_kind_t kind;
  char *title;
  char *body;      /* raw text / markdown / tool output */
  char *render;    /* ANSI for assistant; NULL → draw body */
  int expanded;
  char meta[256];  /* phase / timing / detail */
  char tool_name[CTL_MAX_NAME];
  char tool_id[CTL_MAX_ID];
} block_t;

typedef struct {
  block_t *items;
  int n;
  int cap;
} blocks_t;

typedef struct {
  char text[256];
  char desc[112];
} comp_item_t;

typedef struct {
  cst_agent_t *agent;
  WINDOW *header;
  WINDOW *logw;
  WINDOW *todow;
  WINDOW *status;
  WINDOW *input;
  int rows, cols;
  int input_rows; /* 1..INPUT_MAX_ROWS */
  int todo_rows;

  blocks_t hist; /* sealed blocks */
  block_t live;  /* streaming assistant (kind set when as_live) */
  int as_live;
  char *md_live;
  size_t md_len;
  size_t md_cap;

  int log_scroll;
  char inbuf[INPUT_CAP];
  size_t in_len;
  size_t cur; /* cursor byte offset into inbuf */
  int in_paste;
  int paste_cr; /* last pasted byte was CR (fold CRLF) */
  char status_msg[512];
  char title[128]; /* session title or first prompt, for the header */
  struct timespec ctrlc_at;
  struct timespec turn_t0;
  int spin;

  /* "/" and "@" completion popup */
  comp_item_t comp[COMP_MAX];
  int comp_n, comp_sel, comp_kind; /* kind 1 = slash, 2 = file */
  size_t comp_start;
  int comp_off; /* dismissed with Esc until the input changes */
  int comp_drawn; /* popup rows currently on screen */
  char **files;
  int nfiles;
  struct timespec files_at;

  char *todo;
  int show_todo;
  volatile int need_layout;
  char *pending_prompt; /* set by /retry and /init */

  int busy;
  int details_all; /* /details: expand all tool bodies */
  int awaiting_perm;
  int think_idx; /* hist index of open think, or -1 */
  int last_tool_idx;
  int focus_think_idx;
  struct timespec think_t0;
  int think_timing; /* think_t0 valid */

  /* Prompt history (newest at end). hist_browse=-1 means live buffer. */
  char *prompt_hist[PROMPT_HIST_CAP];
  int prompt_hist_n;
  int hist_browse;

  /* Busy-turn FIFO */
  char *queue[QUEUE_CAP];
  int queue_n;

  /* Permission handshake (worker → main). */
  volatile int perm_ask;
  volatile int perm_ans; /* -1 waiting, else CST_PERM_* */
  char perm_tool[CTL_MAX_NAME];
  char perm_detail[512];
  char *perm_preview;
  char perm_prefix[128];
  int perm_scroll;

  /* ask_user handshake (worker → main). */
  volatile int ask_pending;
  volatile int ask_done;
  int ask_rc;
  int ask_sel;
  int ask_nopts;
  char ask_q[1024];
  char ask_opts[ASK_OPTS_MAX][256];
  char ask_buf[1024];

  pthread_mutex_t mu;
  volatile int dirty;
  volatile int turn_done;
  int turn_rc;
  char turn_err[512];
} tui_t;

/* --- UTF-8 helpers -------------------------------------------------------- */

static size_t utf8_prev_len(const char *s, size_t len) {
  if (len == 0)
    return 0;
  size_t i = len - 1;
  while (i > 0 && ((unsigned char)s[i] & 0xC0) == 0x80)
    i--;
  return len - i;
}

static int utf8_decode(const char *s, size_t avail, wchar_t *wc, size_t *eaten) {
  if (avail == 0)
    return -1;
  mbstate_t st;
  memset(&st, 0, sizeof(st));
  size_t n = mbrtowc(wc, s, avail, &st);
  if (n == (size_t)-1 || n == (size_t)-2 || n == 0) {
    *wc = (unsigned char)s[0];
    *eaten = 1;
    return 0;
  }
  *eaten = n;
  return 0;
}

static int utf8_width(wchar_t wc) {
  int w = wcwidth(wc);
  if (w < 0)
    return 1;
  return w;
}

static int utf8_cols(const char *s, size_t n) {
  int cols = 0;
  size_t i = 0;
  while (i < n) {
    wchar_t wc;
    size_t eaten;
    utf8_decode(s + i, n - i, &wc, &eaten);
    cols += utf8_width(wc);
    i += eaten;
  }
  return cols;
}

static size_t utf8_fit_cols(const char *s, size_t n, int max_cols) {
  int cols = 0;
  size_t i = 0;
  while (i < n) {
    wchar_t wc;
    size_t eaten;
    utf8_decode(s + i, n - i, &wc, &eaten);
    int w = utf8_width(wc);
    if (cols + w > max_cols)
      break;
    cols += w;
    i += eaten;
  }
  return i;
}

static size_t ansi_skip(const char *s, size_t n) {
  if (n < 2 || (unsigned char)s[0] != 0x1b)
    return 0;
  if (s[1] == '[') {
    size_t i = 2;
    while (i < n) {
      unsigned char c = (unsigned char)s[i++];
      if (c >= 0x40 && c <= 0x7e)
        return i;
    }
    return 0;
  }
  return 2;
}

static char *xstrdup(const char *s) {
  if (!s)
    s = "";
  size_t n = strlen(s);
  char *p = malloc(n + 1);
  if (!p)
    return NULL;
  memcpy(p, s, n + 1);
  return p;
}

static char *xstrndup(const char *s, size_t n) {
  char *p = malloc(n + 1);
  if (!p)
    return NULL;
  memcpy(p, s, n);
  p[n] = 0;
  return p;
}

/* --- theme ---------------------------------------------------------------- */

/* OpenCode dark panel — never inherit terminal default bg. */
static void theme_init(void) {
  const char *nc = getenv("NO_COLOR");
  g_nocolor = nc && nc[0];
  const char *asc = getenv("CST_ASCII");
#ifndef _WIN32
  const char *cs = nl_langinfo(CODESET);
  g_utf8 = cs && (strcasecmp(cs, "UTF-8") == 0 || strcasecmp(cs, "utf8") == 0);
#endif
  g_ascii = asc && asc[0] ? asc[0] != '0' : !g_utf8;
  if (!HAS_COLOR())
    return;
  start_color();
  /* Do NOT call use_default_colors(): -1 would leak the terminal theme. */

  short primary = COLOR_YELLOW;
  short panel = COLOR_BLACK;
  short muted = COLOR_CYAN;
  short success = COLOR_GREEN;
  short err = COLOR_RED;
  short assist = COLOR_CYAN;
  short text = COLOR_WHITE;

  if (COLORS >= 256) {
    /* Prefer xterm-256 slots so we don't bleach the 8 ANSI base colors.
     * panel #121212→233, primary #fab283→216, muted #808080→244 */
    primary = 216;
    panel = 233;   /* #121212 — darker than 234 to avoid washed look */
    muted = 244;
    success = 114;
    err = 167;
    assist = 74;   /* soft cyan, not neon */
    text = 250;    /* #bcbcbc — not near-white */
    if (can_change_color()) {
      /* Tune those slots toward exact OpenCode hex */
      init_color(216, 980, 698, 514); /* #fab283 */
      init_color(233, 70, 70, 70);    /* #121212 */
      init_color(244, 502, 502, 502); /* #808080 */
      init_color(250, 720, 720, 720); /* body text */
      init_color(114, 400, 750, 450);
      init_color(167, 850, 320, 320);
      init_color(74, 350, 700, 750);
    }
  } else if (can_change_color() && COLORS >= 8) {
    init_color(COLOR_BLACK, 70, 70, 70);    /* panel #121212 */
    init_color(COLOR_YELLOW, 980, 698, 514); /* primary */
    init_color(COLOR_CYAN, 502, 502, 502);  /* muted (reuse cyan slot) */
    init_color(COLOR_WHITE, 720, 720, 720); /* body text */
    init_color(COLOR_GREEN, 400, 750, 450);
    init_color(COLOR_RED, 850, 320, 320);
    init_color(COLOR_BLUE, 350, 700, 750); /* assist */
    panel = COLOR_BLACK;
    primary = COLOR_YELLOW;
    muted = COLOR_CYAN;
    text = COLOR_WHITE;
    success = COLOR_GREEN;
    err = COLOR_RED;
    assist = COLOR_BLUE;
  }

  /* Header is dark too — primary only as text accent (not a bright bar). */
  init_pair(CP_HEADER, primary, panel);
  init_pair(CP_STATUS, muted, panel);
  init_pair(CP_INPUT, text, panel);
  init_pair(CP_PRIMARY, primary, panel);
  init_pair(CP_ASSIST, assist, panel);
  init_pair(CP_MUTED, muted, panel);
  init_pair(CP_SUCCESS, success, panel);
  init_pair(CP_ERROR, err, panel);
  init_pair(CP_TOOL, primary, panel);
  init_pair(CP_PANEL, text, panel);
  init_pair(CP_SGR_GREEN, success, panel);
  init_pair(CP_SGR_YELLOW, primary, panel);
  init_pair(CP_SGR_CYAN, assist, panel);
  if (COLORS >= 256)
    init_pair(CP_SGR_MAGENTA, 176, panel);
  else
    init_pair(CP_SGR_MAGENTA, COLOR_MAGENTA, panel);

  /* Diff rows: high-contrast xterm-256 palette only.
   * Do NOT init_color() cube indices 16–21 — many terminals ignore it and leave
   * default blues, which made add/del rows unreadable (dark-on-blue). */
  if (COLORS >= 256) {
    init_pair(CP_DIFF_ADD, 157, 22);  /* #afff87 on #005f00 */
    init_pair(CP_DIFF_DEL, 203, 52);  /* #ff5f5f on #5f0000 */
    init_pair(CP_DIFF_CTX, 252, panel); /* bright gray on panel */
  } else {
    init_pair(CP_DIFF_ADD, COLOR_GREEN, COLOR_BLACK);
    init_pair(CP_DIFF_DEL, COLOR_RED, COLOR_BLACK);
    init_pair(CP_DIFF_CTX, COLOR_WHITE, COLOR_BLACK);
  }
}

static void theme_paint_root(void) {
  if (!HAS_COLOR())
    return;
  wbkgd(stdscr, COLOR_PAIR(CP_PANEL));
  werase(stdscr);
  wnoutrefresh(stdscr);
}

/* --- blocks --------------------------------------------------------------- */

static void block_clear(block_t *b) {
  if (!b)
    return;
  free(b->title);
  free(b->body);
  free(b->render);
  memset(b, 0, sizeof(*b));
}

static void blocks_init(blocks_t *bs) {
  bs->items = calloc((size_t)BLOCKS_INIT, sizeof(block_t));
  bs->n = 0;
  bs->cap = bs->items ? BLOCKS_INIT : 0;
}

static void blocks_free(blocks_t *bs) {
  if (!bs)
    return;
  for (int i = 0; i < bs->n; i++)
    block_clear(&bs->items[i]);
  free(bs->items);
  bs->items = NULL;
  bs->n = bs->cap = 0;
}

static void blocks_clear(blocks_t *bs) {
  for (int i = 0; i < bs->n; i++)
    block_clear(&bs->items[i]);
  bs->n = 0;
}

static block_t *blocks_push(blocks_t *bs) {
  if (!bs->items)
    return NULL;
  if (bs->n >= bs->cap) {
    int nc = bs->cap * 2;
    block_t *ni = realloc(bs->items, (size_t)nc * sizeof(block_t));
    if (!ni)
      return NULL;
    memset(ni + bs->cap, 0, (size_t)(nc - bs->cap) * sizeof(block_t));
    bs->items = ni;
    bs->cap = nc;
  }
  block_t *b = &bs->items[bs->n++];
  memset(b, 0, sizeof(*b));
  return b;
}

static void block_set_title(block_t *b, const char *t) {
  free(b->title);
  b->title = xstrdup(t ? t : "");
}

static void block_set_body(block_t *b, const char *s, size_t n) {
  free(b->body);
  b->body = n ? xstrndup(s, n) : xstrdup("");
}

static void block_append_body(block_t *b, const char *s, size_t n) {
  if (!s || !n)
    return;
  size_t old = b->body ? strlen(b->body) : 0;
  char *nb = realloc(b->body, old + n + 1);
  if (!nb)
    return;
  memcpy(nb + old, s, n);
  nb[old + n] = 0;
  b->body = nb;
}

/* Markdown → ANSI via Sashidown. */
static int md_to_ansi_dyn(const char *md, size_t md_len, char **outp,
                          size_t *out_len) {
  if (!md || !outp)
    return -1;
  if (md_len == 0) {
    *outp = NULL;
    if (out_len)
      *out_len = 0;
    return 0;
  }
  size_t cap = ANSI_INIT;
  char *out = malloc(cap);
  if (!out)
    return -1;
  for (;;) {
    size_t n = 0;
    int rc = sashidown_convert(md, md_len, out, cap, &n, SASHIDOWN_FMT_ANSI);
    if (rc == 0) {
      *outp = out;
      if (out_len)
        *out_len = n;
      return 0;
    }
    size_t nc = cap * 2;
    if (nc < md_len * 4)
      nc = md_len * 4;
    if (nc > 16 * 1024 * 1024) {
      free(out);
      out = malloc(md_len + 1);
      if (!out)
        return -1;
      memcpy(out, md, md_len);
      out[md_len] = 0;
      *outp = out;
      if (out_len)
        *out_len = md_len;
      return 0;
    }
    char *nb = realloc(out, nc);
    if (!nb) {
      free(out);
      return -1;
    }
    out = nb;
    cap = nc;
  }
}

static void block_render_assistant(block_t *b) {
  free(b->render);
  b->render = NULL;
  if (!b->body || !b->body[0])
    return;
  char *ansi = NULL;
  size_t n = 0;
  if (md_to_ansi_dyn(b->body, strlen(b->body), &ansi, &n) == 0 && ansi) {
    b->render = ansi;
  }
}

static const char *tool_prefix(const char *name) {
  if (!name)
    return "•";
  if (strcmp(name, "run_shell") == 0)
    return "$";
  if (cst_tool_is_write(name))
    return "←";
  if (strcmp(name, "read_file") == 0)
    return "✱";
  if (strcmp(name, "web_fetch") == 0)
    return "%";
  return "•";
}

static void tool_arg_summary(const ctl_tool_call_t *call, char *out,
                             size_t out_sz) {
  static const struct {
    const char *tool, *key;
  } PREFER[] = {{"run_shell", "cmd"},       {"read_file", "path"},
                {"write_file", "path"},     {"edit_file", "path"},
                {"delete_file", "path"},    {"move_file", "from"},
                {"list_dir", "path"},       {"glob", "pattern"},
                {"grep", "pattern"},        {"web_fetch", "url"},
                {"ask_user", "question"},   {"apply_patch", "patch"}};
  out[0] = 0;
  if (!call || out_sz == 0)
    return;
  if (strcmp(call->name, "todo_write") == 0) {
    snprintf(out, out_sz, "update task list");
    return;
  }
  const char *prefer = NULL;
  for (size_t i = 0; i < sizeof(PREFER) / sizeof(PREFER[0]); i++)
    if (strcmp(call->name, PREFER[i].tool) == 0)
      prefer = PREFER[i].key;
  int pick = -1;
  for (int i = 0; i < call->nargs; i++)
    if (prefer && strcmp(call->args[i].key, prefer) == 0)
      pick = i;
  if (pick < 0 && call->nargs > 0)
    pick = 0;
  if (pick < 0 || !call->args[pick].value)
    return;
  const char *v = call->args[pick].value;
  size_t len = call->args[pick].value_len ? call->args[pick].value_len
                                          : strlen(v);
  size_t nl = strcspn(v, "\n");
  int cut = len > 80 || nl < len;
  if (nl < len)
    len = nl;
  if (len > 80)
    len = cst_utf8_floor(v, 80);
  snprintf(out, out_sz, "%.*s%s", (int)len, v, cut ? "…" : "");
}

static void tui_lock(tui_t *t) { pthread_mutex_lock(&t->mu); }
static void tui_unlock(tui_t *t) { pthread_mutex_unlock(&t->mu); }
static void tui_mark_dirty(tui_t *t) { t->dirty = 1; }

static void set_status_locked(tui_t *t, const char *msg) {
  snprintf(t->status_msg, sizeof(t->status_msg), "%s", msg ? msg : "");
  tui_mark_dirty(t);
}

static void set_status(tui_t *t, const char *msg) {
  tui_lock(t);
  set_status_locked(t, msg);
  tui_unlock(t);
}

static void status_idle(tui_t *t) {
  if (t->queue_n > 0)
    snprintf(t->status_msg, sizeof(t->status_msg),
             "ready · %d queued · empty Enter sends the next one", t->queue_n);
  else
    snprintf(t->status_msg, sizeof(t->status_msg),
             "ready · / commands · @ files · Tab thought · PgUp scroll · "
             "Ctrl+C twice quits");
}

/* --- live assistant ------------------------------------------------------- */

static void live_end_cleanup(tui_t *t) {
  block_clear(&t->live);
  free(t->md_live);
  t->md_live = NULL;
  t->md_len = 0;
  t->md_cap = 0;
  t->as_live = 0;
}

static void live_begin(tui_t *t) {
  live_end_cleanup(t);
  t->md_cap = MD_INIT;
  t->md_live = calloc(1, t->md_cap);
  t->md_len = 0;
  t->live.kind = BLK_ASSISTANT;
  block_set_title(&t->live, "Assistant");
  t->live.expanded = 1;
  t->as_live = 1;
}

static void live_feed(tui_t *t, const char *text, size_t len) {
  if (!t->as_live || !text || !len)
    return;
  if (t->md_len + len + 1 > t->md_cap) {
    size_t nc = t->md_cap * 2;
    while (nc < t->md_len + len + 1)
      nc *= 2;
    char *nb = realloc(t->md_live, nc);
    if (!nb)
      return;
    t->md_live = nb;
    t->md_cap = nc;
  }
  memcpy(t->md_live + t->md_len, text, len);
  t->md_len += len;
  t->md_live[t->md_len] = 0;
  /* During stream show raw markdown; convert on seal. */
  free(t->live.body);
  t->live.body = xstrndup(t->md_live, t->md_len);
  free(t->live.render);
  t->live.render = NULL;
}

static void live_seal(tui_t *t) {
  if (!t->as_live)
    return;
  block_t *b = blocks_push(&t->hist);
  if (b) {
    b->kind = BLK_ASSISTANT;
    block_set_title(b, "Assistant");
    if (t->md_len)
      block_set_body(b, t->md_live, t->md_len);
    else if (t->live.body)
      block_set_body(b, t->live.body, strlen(t->live.body));
    b->expanded = 1;
    block_render_assistant(b);
  }
  live_end_cleanup(t);
}

static void collapse_open_think(tui_t *t) {
  if (t->think_idx < 0 || t->think_idx >= t->hist.n)
    return;
  block_t *th = &t->hist.items[t->think_idx];
  if (th->kind != BLK_THINK)
    return;
  th->expanded = 0;
  char title[64];
  if (t->think_timing) {
    struct timespec now;
    clock_gettime(CLOCK_MONOTONIC, &now);
    double sec = (double)(now.tv_sec - t->think_t0.tv_sec) +
                 (double)(now.tv_nsec - t->think_t0.tv_nsec) / 1e9;
    if (sec < 0)
      sec = 0;
    if (sec < 1.0)
      snprintf(title, sizeof(title), "Thought · %.1fs", sec);
    else
      snprintf(title, sizeof(title), "Thought · %.1fs", sec);
    t->think_timing = 0;
  } else {
    snprintf(title, sizeof(title), "Thought");
  }
  block_set_title(th, title);
  t->think_idx = -1;
}

static int find_tool_block(tui_t *t, const char *id) {
  if (!id || !id[0])
    return -1;
  for (int i = t->hist.n - 1; i >= 0; i--) {
    block_t *b = &t->hist.items[i];
    if (b->kind == BLK_TOOL && strcmp(b->tool_id, id) == 0)
      return i;
  }
  return -1;
}

static int msg_is_tool_result(const cst_message_t *m) {
  return m && (m->role == CST_ROLE_TOOL ||
               (m->role == CST_ROLE_USER && m->tool_call_id[0]));
}

/* Strip the "[tool …]" / "result <id> exit=N <n>" header and "end" trailer. */
static void tool_result_view(const char *content, const char **body,
                             size_t *len) {
  const char *s = content ? content : "";
  size_t n = strlen(s);
  int framed = strncmp(s, "result ", 7) == 0;
  if (framed || strncmp(s, "[tool ", 6) == 0) {
    const char *nl = strchr(s, '\n');
    if (nl) {
      n -= (size_t)(nl + 1 - s);
      s = nl + 1;
    } else {
      n = 0;
    }
  }
  if (framed && n >= 4 && memcmp(s + n - 4, "\nend", 4) == 0)
    n -= 4;
  else if (framed && n == 3 && memcmp(s, "end", 3) == 0)
    n = 0;
  *body = s;
  *len = n;
}

static void attach_tool_output_from_session(tui_t *t, block_t *b) {
  if (!b || b->kind != BLK_TOOL || !b->tool_id[0])
    return;
  cst_session_t *s = cst_agent_session(t->agent);
  if (!s)
    return;
  cst_session_lock(s);
  int n = cst_session_count(s);
  for (int i = n - 1; i >= 0; i--) {
    const cst_message_t *m = cst_session_get(s, i);
    if (!msg_is_tool_result(m))
      continue;
    if (strcmp(m->tool_call_id, b->tool_id) != 0)
      continue;
    const char *body;
    size_t len;
    tool_result_view(m->content, &body, &len);
    block_set_body(b, body, len);
    break;
  }
  cst_session_unlock(s);
}

/* --- drawing: SGR --------------------------------------------------------- */

typedef struct {
  int attrs;
  int pair;
} sty_t;

static void sgr_apply(sty_t *st, int code) {
  switch (code) {
  case 0:
    st->attrs = 0;
    st->pair = 0;
    break;
  case 1:
    st->attrs |= A_BOLD;
    break;
  case 2:
    st->attrs |= A_DIM;
    break;
  case 3:
#ifdef A_ITALIC
    st->attrs |= A_ITALIC;
#endif
    break;
  case 4:
    st->attrs |= A_UNDERLINE;
    break;
  case 7:
    st->attrs |= A_REVERSE;
    break;
  case 22:
    st->attrs &= ~(A_BOLD | A_DIM);
    break;
  case 23:
#ifdef A_ITALIC
    st->attrs &= ~A_ITALIC;
#endif
    break;
  case 24:
    st->attrs &= ~A_UNDERLINE;
    break;
  case 27:
    st->attrs &= ~A_REVERSE;
    break;
  case 31:
  case 91:
    st->pair = CP_ERROR;
    break;
  case 32:
  case 92:
    st->pair = CP_SGR_GREEN;
    break;
  case 33:
  case 93:
    st->pair = CP_SGR_YELLOW;
    break;
  case 36:
  case 96:
    st->pair = CP_SGR_CYAN;
    break;
  case 35:
  case 95:
    st->pair = CP_SGR_MAGENTA;
    break;
  case 39:
    st->pair = 0;
    break;
  default:
    break;
  }
}

static size_t sgr_parse(const char *s, size_t n, sty_t *st) {
  if (n < 3 || (unsigned char)s[0] != 0x1b || s[1] != '[')
    return 0;
  size_t i = 2;
  int val = 0, have = 0;
  while (i < n) {
    unsigned char c = (unsigned char)s[i++];
    if (c >= '0' && c <= '9') {
      val = val * 10 + (c - '0');
      have = 1;
    } else if (c == ';') {
      sgr_apply(st, have ? val : 0);
      val = 0;
      have = 0;
    } else if (c == 'm') {
      sgr_apply(st, have ? val : 0);
      return i;
    } else {
      return 0;
    }
  }
  return 0;
}

static wchar_t ascii_glyph(wchar_t wc) {
  if (!g_ascii || wc < 128)
    return wc;
  switch (wc) {
  case 0x2503: /* ┃ */
  case 0x2502: /* │ */
    return L'|';
  case 0x2500: /* ─ */
  case 0x00b7: /* · */
    return L'-';
  case 0x25bc: /* ▼ */
  case 0x2193: /* ↓ */
    return L'v';
  case 0x25b6: /* ▶ */
  case 0x25b8: /* ▸ */
  case 0x2192: /* → */
    return L'>';
  case 0x2190: /* ← */
    return L'<';
  case 0x2191: /* ↑ */
    return L'^';
  case 0x2026: /* … */
    return L'.';
  case 0x2713: /* ✓ */
    return L'x';
  case 0x25cb: /* ○ */
    return L'o';
  default:
    return g_utf8 ? wc : L'?';
  }
}

static int put_wc(WINDOW *win, int y, int col, wchar_t wc, int attrs) {
  wc = ascii_glyph(wc);
  cchar_t cc;
  wchar_t wstr[2] = {wc, 0};
  short pair = (short)PAIR_NUMBER(attrs);
  attr_t a = (attr_t)(attrs & ~(attr_t)A_COLOR);
  if (setcchar(&cc, wstr, a, pair, NULL) == ERR) {
    if (wc < 128)
      mvwaddch(win, y, col, (chtype)wc | (chtype)attrs);
    else
      mvwaddstr(win, y, col, "?");
    return 1;
  }
  mvwadd_wch(win, y, col, &cc);
  return utf8_width(wc);
}

/* Flatten blocks into display lines (plain text with optional ANSI in body). */
typedef struct {
  char *text; /* owned line content (may include ANSI) */
  int pair;   /* base color pair for whole line (0 = default) */
  int bold;
  int dim;
  int indent; /* leading columns already accounted in text */
} dline_t;

typedef struct {
  dline_t *lines;
  int n;
  int cap;
} dlines_t;

static void dlines_free(dlines_t *dl) {
  if (!dl)
    return;
  for (int i = 0; i < dl->n; i++)
    free(dl->lines[i].text);
  free(dl->lines);
  dl->lines = NULL;
  dl->n = dl->cap = 0;
}

static int dlines_push(dlines_t *dl, const char *text, int pair, int bold,
                       int dim) {
  if (dl->n >= dl->cap) {
    int nc = dl->cap ? dl->cap * 2 : 256;
    dline_t *ni = realloc(dl->lines, (size_t)nc * sizeof(dline_t));
    if (!ni)
      return -1;
    dl->lines = ni;
    dl->cap = nc;
  }
  dline_t *L = &dl->lines[dl->n++];
  L->text = xstrdup(text ? text : "");
  L->pair = pair;
  L->bold = bold;
  L->dim = dim;
  L->indent = 0;
  return 0;
}

static void push_wrapped(dlines_t *dl, const char *prefix, const char *body,
                         int width, int pair, int bold, int dim, int ansi) {
  (void)ansi;
  char line[4096];
  int pref_cols = prefix ? utf8_cols(prefix, strlen(prefix)) : 0;
  int body_w = width - pref_cols;
  if (body_w < 8)
    body_w = 8;

  if (!body || !body[0]) {
    snprintf(line, sizeof(line), "%s", prefix ? prefix : "");
    dlines_push(dl, line, pair, bold, dim);
    return;
  }

  /* Walk body; for ANSI text, wrap on visible columns skipping SGR. */
  size_t n = strlen(body);
  size_t i = 0;
  int first = 1;
  while (i < n && dl->n < MAX_RENDER_LINES) {
    size_t start = i;
    int col = 0;
    while (i < n) {
      size_t sg = 0;
      if ((unsigned char)body[i] == 0x1b) {
        sty_t dummy = {0};
        sg = sgr_parse(body + i, n - i, &dummy);
        if (!sg)
          sg = ansi_skip(body + i, n - i);
        if (sg) {
          i += sg;
          continue;
        }
      }
      if (body[i] == '\n') {
        i++;
        break;
      }
      wchar_t wc;
      size_t eaten;
      utf8_decode(body + i, n - i, &wc, &eaten);
      int cw = utf8_width(wc);
      if (col + cw > body_w && col > 0)
        break;
      col += cw;
      i += eaten;
      if (col >= body_w)
        break;
    }
    size_t chunk = i - start;
    /* trim trailing newline already consumed */
    if (chunk > 0 && body[start + chunk - 1] == '\n')
      chunk--;
    if (first && prefix) {
      if (chunk + strlen(prefix) + 1 < sizeof(line)) {
        memcpy(line, prefix, strlen(prefix));
        memcpy(line + strlen(prefix), body + start, chunk);
        line[strlen(prefix) + chunk] = 0;
      } else {
        snprintf(line, sizeof(line), "%s", prefix);
      }
      first = 0;
    } else {
      /* continuation indent matching prefix visual width */
      int pad = pref_cols;
      if (pad < 0)
        pad = 0;
      if (pad > 40)
        pad = 40;
      memset(line, ' ', (size_t)pad);
      if (chunk + (size_t)pad + 1 < sizeof(line)) {
        memcpy(line + pad, body + start, chunk);
        line[pad + chunk] = 0;
      } else {
        line[pad] = 0;
      }
    }
    dlines_push(dl, line, pair, bold, dim);
    if (i < n && body[i - 1] != '\n' && col >= body_w) {
      /* soft wrap — already advanced */
    }
  }
}

static void push_body_preview(dlines_t *dl, const char *body, int width,
                              int pair, int expanded, int max_lines) {
  if (!body || !body[0])
    return;
  if (expanded) {
    push_wrapped(dl, "  ", body, width, pair, 0, 1, 0);
    return;
  }
  const char *p = body;
  int shown = 0;
  while (*p && shown < max_lines) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    char tmp[1024];
    if (len >= sizeof(tmp))
      len = sizeof(tmp) - 1;
    memcpy(tmp, p, len);
    tmp[len] = 0;
    push_wrapped(dl, "  ", tmp, width, pair, 0, 1, 0);
    shown++;
    if (!nl)
      break;
    p = nl + 1;
  }
  if (*p)
    dlines_push(dl, "  …", pair, 0, 1);
}

static int body_looks_like_diff(const char *body) {
  if (!body || !body[0])
    return 0;
  return strstr(body, "\n--- ") || strstr(body, "\n+++ ") ||
         strstr(body, "\n@@ ") || strstr(body, "\n@@-") ||
         strncmp(body, "--- ", 4) == 0 || strncmp(body, "diff ", 5) == 0 ||
         strstr(body, "\n--- a/") || strstr(body, "\n+++ b/");
}

static void diff_extract_path(const char *body, const char *fallback,
                              char *out, size_t out_sz) {
  if (!out || out_sz == 0)
    return;
  out[0] = 0;
  if (body) {
    const char *p = body;
    while (*p) {
      const char *nl = strchr(p, '\n');
      size_t len = nl ? (size_t)(nl - p) : strlen(p);
      if (len > 6 && strncmp(p, "wrote ", 6) == 0) {
        const char *s = p + 6;
        size_t n = len - 6;
        /* trim " (N bytes)" */
        const char *sp = memchr(s, ' ', n);
        if (sp)
          n = (size_t)(sp - s);
        if (n >= out_sz)
          n = out_sz - 1;
        memcpy(out, s, n);
        out[n] = 0;
        return;
      }
      if (len > 6 && strncmp(p, "+++ b/", 6) == 0) {
        size_t n = len - 6;
        if (n >= out_sz)
          n = out_sz - 1;
        memcpy(out, p + 6, n);
        out[n] = 0;
        return;
      }
      if (len > 6 && strncmp(p, "--- a/", 6) == 0) {
        size_t n = len - 6;
        if (n >= out_sz)
          n = out_sz - 1;
        memcpy(out, p + 6, n);
        out[n] = 0;
        /* keep scanning for +++ / wrote */
      }
      if (!nl)
        break;
      p = nl + 1;
    }
  }
  if (!out[0] && fallback && fallback[0]) {
    snprintf(out, out_sz, "%s", fallback);
  }
}

static int parse_hunk_at(const char *line, int *old_ln, int *new_ln) {
  /* @@ -old[,n] +new[,n] @@ */
  if (line[0] != '@' || line[1] != '@')
    return 0;
  const char *p = line;
  while (*p && *p != '-')
    p++;
  if (*p != '-')
    return 0;
  p++;
  int o = 0, n = 0;
  if (sscanf(p, "%d", &o) != 1)
    return 0;
  while (*p && *p != '+')
    p++;
  if (*p != '+')
    return 0;
  p++;
  if (sscanf(p, "%d", &n) != 1)
    return 0;
  if (old_ln)
    *old_ln = o;
  if (new_ln)
    *new_ln = n;
  return 1;
}

typedef struct {
  int additions;
  int deletions;
  int content_lines;
} diff_stats_t;

static void diff_count_stats(const char *body, diff_stats_t *st) {
  memset(st, 0, sizeof(*st));
  if (!body)
    return;
  const char *p = body;
  while (*p) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    if (len == 0) {
      /* empty */
    } else if (strncmp(p, "---", 3) == 0 || strncmp(p, "+++", 3) == 0 ||
               strncmp(p, "diff ", 5) == 0 || strncmp(p, "index ", 6) == 0 ||
               strncmp(p, "@@", 2) == 0 || strncmp(p, "wrote ", 6) == 0 ||
               (p[0] == '[' && strstr(p, "tool "))) {
      /* skip meta */
    } else if (p[0] == '+') {
      st->additions++;
      st->content_lines++;
    } else if (p[0] == '-') {
      st->deletions++;
      st->content_lines++;
    } else if (p[0] == ' ' || p[0] == '\\') {
      st->content_lines++;
    }
    if (!nl)
      break;
    p = nl + 1;
  }
}

/* OpenCode-style: strip ---/+++/@@, line numbers, add/del backgrounds. */
static void push_structured_diff(dlines_t *dl, const char *body, int width,
                                 int unlimited, int fold_limit) {
  if (!body || !body[0])
    return;
  int old_ln = 0, new_ln = 0;
  int shown = 0;
  int total_content = 0;
  /* First pass: count content lines for fold message */
  {
    diff_stats_t st;
    diff_count_stats(body, &st);
    total_content = st.content_lines;
  }
  int limit = unlimited ? 1000000 : fold_limit;
  if (limit < 1)
    limit = 1;

  const char *p = body;
  while (*p) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    char raw[1024];
    if (len >= sizeof(raw))
      len = sizeof(raw) - 1;
    memcpy(raw, p, len);
    raw[len] = 0;

    int skip = 0;
    if (raw[0] == 0)
      skip = 1;
    else if (strncmp(raw, "wrote ", 6) == 0)
      skip = 1;
    else if (raw[0] == '[' && strstr(raw, "tool "))
      skip = 1;
    else if (strncmp(raw, "---", 3) == 0 || strncmp(raw, "+++", 3) == 0 ||
             strncmp(raw, "diff ", 5) == 0 || strncmp(raw, "index ", 6) == 0)
      skip = 1;
    else if (strncmp(raw, "@@", 2) == 0) {
      parse_hunk_at(raw, &old_ln, &new_ln);
      skip = 1;
    } else if (raw[0] == '\\') {
      /* "\ No newline at end of file" */
      skip = 1;
    }

    if (!skip && (raw[0] == '+' || raw[0] == '-' || raw[0] == ' ')) {
      if (shown >= limit) {
        /* keep counting via total_content; stop emitting */
        break;
      }
      char kind = raw[0];
      const char *content = raw + 1;
      int lnum = 0;
      char mark = ' ';
      int pair = CP_DIFF_CTX;
      if (kind == '+') {
        lnum = new_ln++;
        mark = '+';
        pair = CP_DIFF_ADD;
      } else if (kind == '-') {
        lnum = old_ln++;
        mark = '-';
        pair = CP_DIFF_DEL;
      } else {
        lnum = new_ln;
        old_ln++;
        new_ln++;
        mark = ' ';
        pair = CP_DIFF_CTX;
      }

      char line[1200];
      /* │  12+│ content  — left border + gutter + body */
      int body_w = width - 8;
      if (body_w < 8)
        body_w = 8;
      char clipped[1024];
      size_t clen = strlen(content);
      /* column-clip roughly by bytes for MVP */
      if ((int)clen > body_w) {
        int keep = body_w > 3 ? body_w - 3 : body_w;
        memcpy(clipped, content, (size_t)keep);
        if (body_w > 3)
          memcpy(clipped + keep, "...", 4);
        else
          clipped[keep] = 0;
        content = clipped;
      }
      snprintf(line, sizeof(line), "│%4d%c│ %s", lnum, mark, content);
      /* Pad to width so row background fills like OpenCode. */
      {
        int cols = utf8_cols(line, strlen(line));
        size_t llen = strlen(line);
        while (cols < width && llen + 1 < sizeof(line)) {
          line[llen++] = ' ';
          line[llen] = 0;
          cols++;
        }
      }
      dlines_push(dl, line, pair, kind != ' ', 0);
      shown++;
    }

    if (!nl)
      break;
    p = nl + 1;
  }

  if (!unlimited && total_content > shown) {
    char more[96];
    snprintf(more, sizeof(more), "│ … %d more lines · /details",
             total_content - shown);
    dlines_push(dl, more, CP_MUTED, 0, 1);
  }
}

static void push_diff_or_body(dlines_t *dl, const char *body, int width,
                              int default_pair, int expanded, int max_lines,
                              int details_all) {
  if (!body || !body[0])
    return;
  if (!body_looks_like_diff(body)) {
    push_body_preview(dl, body, width, default_pair, expanded || details_all,
                      max_lines);
    return;
  }
  /* Auto-expanded write cards still fold at DIFF_FOLD_LINES unless /details. */
  int unlimited = details_all;
  int fold = expanded ? DIFF_FOLD_LINES : max_lines;
  if (!expanded && !details_all)
    fold = 0; /* title-only when collapsed */
  if (fold == 0 && !unlimited)
    return;
  push_structured_diff(dl, body, width, unlimited, fold);
}

static void block_to_lines(const block_t *b, int width, int details_all,
                           dlines_t *dl) {
  char prefix[128];
  char head[512];

  switch (b->kind) {
  case BLK_USER:
    snprintf(prefix, sizeof(prefix), "┃ ");
    dlines_push(dl, "┃ You", CP_PRIMARY, 1, 0);
    push_wrapped(dl, prefix, b->body ? b->body : "", width, CP_PRIMARY, 0, 0,
                 0);
    dlines_push(dl, "", 0, 0, 0);
    break;

  case BLK_ASSISTANT: {
    dlines_push(dl, "┃ Assistant", CP_ASSIST, 1, 0);
    const char *src = b->render ? b->render : (b->body ? b->body : "");
    push_wrapped(dl, "┃ ", src, width, CP_ASSIST, 0, 0, 1);
    dlines_push(dl, "", 0, 0, 0);
    break;
  }

  case BLK_THINK:
    if (b->expanded) {
      snprintf(head, sizeof(head), "▼ %s", b->title ? b->title : "Thought");
      dlines_push(dl, head, CP_MUTED, 0, 1);
      push_wrapped(dl, "  ", b->body ? b->body : "", width, CP_MUTED, 0, 1, 0);
    } else {
      /* One-liner: title + truncated body hint */
      const char *body = b->body ? b->body : "";
      size_t bl = strlen(body);
      while (bl > 0 && (body[bl - 1] == '\n' || body[bl - 1] == ' '))
        bl--;
      char one[200];
      size_t take = bl > 60 ? 60 : bl;
      /* skip to first non-space for preview */
      size_t off = 0;
      while (off < take && (body[off] == ' ' || body[off] == '\n'))
        off++;
      snprintf(one, sizeof(one), "▶ %s  %.*s%s",
               b->title ? b->title : "Thought", (int)(take > off ? take - off : 0),
               body + off, bl > 60 ? "…" : "");
      dlines_push(dl, one, CP_MUTED, 0, 1);
    }
    break;

  case BLK_TOOL: {
    const char *px = tool_prefix(b->tool_name);
    int exp = details_all || b->expanded;
    int denied = (strncmp(b->meta, "denied", 6) == 0);
    int is_write = (strcmp(b->tool_name, "write_file") == 0);
    int is_file_edit = cst_tool_is_write(b->tool_name);
    const char *verb_done = is_write ? "Wrote" : "Edit";
    const char *verb_run = is_write ? "Write" : "Edit";
    if (strcmp(b->tool_name, "delete_file") == 0)
      verb_done = "Deleted", verb_run = "Delete";
    else if (strcmp(b->tool_name, "move_file") == 0)
      verb_done = "Moved", verb_run = "Move";
    int done = (strncmp(b->meta, "exit=", 5) == 0) ||
               (strcmp(b->meta, "done") == 0) ||
               (b->body && body_looks_like_diff(b->body));

    if (is_file_edit && !denied) {
      char path[256];
      diff_extract_path(b->body, b->title, path, sizeof(path));
      if (!path[0] && b->title && b->title[0])
        snprintf(path, sizeof(path), "%s", b->title);
      if (!path[0])
        snprintf(path, sizeof(path), "file");

      diff_stats_t st = {0};
      if (b->body)
        diff_count_stats(b->body, &st);

      char head[512];
      if (done) {
        /* OpenCode: ← Wrote path / ← Edit path  +N -M */
        snprintf(head, sizeof(head),
                 "│ ← %s %.200s   \033[32m+%d\033[0m  \033[31m-%d\033[0m",
                 verb_done, path, st.additions, st.deletions);
      } else {
        snprintf(head, sizeof(head), "│ ← %s %.200s  %.100s", verb_run, path,
                 b->meta[0] ? b->meta : "…");
      }
      dlines_push(dl, head, CP_MUTED, 0, 0);
      if (done || exp)
        push_diff_or_body(dl, b->body, width, CP_MUTED, b->expanded,
                          TOOL_PREVIEW_LINES, details_all);
    } else {
      char status_short[96];
      status_short[0] = 0;
      if (denied) {
        snprintf(status_short, sizeof(status_short), "denied");
      } else if (strncmp(b->meta, "exit=", 5) == 0) {
        snprintf(status_short, sizeof(status_short), "done  %.80s", b->meta);
      } else if (b->meta[0]) {
        snprintf(status_short, sizeof(status_short), "%.80s", b->meta);
      }
      snprintf(head, sizeof(head), "%s %s  %s%s%s", px,
               b->tool_name[0] ? b->tool_name : "tool",
               b->title ? b->title : "",
               status_short[0] ? "  " : "", status_short);
      dlines_push(dl, head, denied ? CP_ERROR : CP_TOOL, 1, 0);
      push_diff_or_body(dl, b->body, width, denied ? CP_ERROR : CP_MUTED, exp,
                        TOOL_PREVIEW_LINES, details_all);
    }
    break;
  }

  case BLK_STATUS:
  case BLK_SYSTEM:
    snprintf(head, sizeof(head), "%s%s%s", b->title ? b->title : "",
             (b->title && b->body && b->body[0]) ? " " : "",
             b->body ? b->body : "");
    dlines_push(dl, head, CP_MUTED, 0, 1);
    break;
  }
}

static void build_display(tui_t *t, dlines_t *dl, int width) {
  dlines_free(dl);
  dl->lines = NULL;
  dl->n = dl->cap = 0;
  for (int i = 0; i < t->hist.n; i++)
    block_to_lines(&t->hist.items[i], width, t->details_all, dl);
  if (t->as_live)
    block_to_lines(&t->live, width, t->details_all, dl);
}

static void draw_ansi_line(WINDOW *win, int y, int maxw, const char *s,
                           int base_pair, int base_bold, int base_dim) {
  sty_t sty = {0};
  sty.pair = base_pair;
  if (base_bold)
    sty.attrs |= A_BOLD;
  if (base_dim)
    sty.attrs |= A_DIM;
  int col = 0;
  size_t n = s ? strlen(s) : 0;
  size_t i = 0;
  while (i < n && col < maxw) {
    size_t sg = sgr_parse(s + i, n - i, &sty);
    if (sg) {
      i += sg;
      continue;
    }
    size_t skip = ansi_skip(s + i, n - i);
    if (skip) {
      i += skip;
      continue;
    }
    wchar_t wc;
    size_t eaten;
    utf8_decode(s + i, n - i, &wc, &eaten);
    wc = ascii_glyph(wc);
    int cw = utf8_width(wc);
    if (col + cw > maxw)
      break;
    int attrs = sty.attrs;
    if (sty.pair && HAS_COLOR())
      attrs |= COLOR_PAIR(sty.pair);
    else if (base_pair && HAS_COLOR())
      attrs |= COLOR_PAIR(base_pair);
    put_wc(win, y, col, wc, attrs);
    col += cw;
    i += eaten;
  }
}

static double since_ms(const struct timespec *t0) {
  struct timespec now;
  clock_gettime(CLOCK_MONOTONIC, &now);
  return (double)(now.tv_sec - t0->tv_sec) * 1000.0 +
         (double)(now.tv_nsec - t0->tv_nsec) / 1e6;
}

static void draw_header(tui_t *t) {
  if (!t->header)
    return;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  werase(t->header);
  if (HAS_COLOR())
    wbkgd(t->header, COLOR_PAIR(CP_HEADER));
  if (!cfg) {
    wrefresh(t->header);
    return;
  }
  char line[640], right[96] = "";
  const char *dot = g_ascii ? " | " : " · ";
  long win = cst_model_context_tokens(cfg->model);
  long used = cst_agent_last_prompt_tokens(t->agent);
  int pct = win > 0 ? (int)(used * 100 / win) : 0;
  const char *pc = pct >= 80 ? "\033[31m" : pct >= 60 ? "\033[33m" : "";
  const char *eff = cst_effort_wire(cfg->provider, cfg->model, cfg->effort)
                        ? cfg->effort
                        : NULL;
  int k = snprintf(line, sizeof(line),
                   " CST-Agent%s%s/%s%s%s%s%s%sctx %s%d%%\033[39m", dot,
                   cfg->provider, cfg->model, eff ? dot : "", eff ? eff : "",
                   dot, cst_protocol_name(cfg->protocol), dot, pc, pct);
  if (k > 0 && (size_t)k < sizeof(line) && t->title[0])
    k += snprintf(line + k, sizeof(line) - (size_t)k, "%s%.40s", dot, t->title);
  if (k > 0 && (size_t)k < sizeof(line) && cfg->auto_approve)
    snprintf(line + k, sizeof(line) - (size_t)k, "%s\033[31;1mYOLO\033[0m", dot);
  if (t->busy) {
    static const char *const uni[] = {"⠋", "⠙", "⠹", "⠸", "⠼",
                                      "⠴", "⠦", "⠧", "⠇", "⠏"};
    static const char *const asc[] = {"|", "/", "-", "\\"};
    const char *f = g_ascii ? asc[t->spin % 4] : uni[t->spin % 10];
    snprintf(right, sizeof(right), "%s working %.0fs ", f,
             since_ms(&t->turn_t0) / 1000.0);
  }
  int rw = utf8_cols(right, strlen(right));
  draw_ansi_line(t->header, 0, t->cols - rw - 1, line, CP_HEADER, 1, 0);
  if (rw) {
    if (HAS_COLOR())
      wattron(t->header, COLOR_PAIR(CP_PRIMARY));
    mvwaddstr(t->header, 0, t->cols - rw - 1, right);
    if (HAS_COLOR())
      wattroff(t->header, COLOR_PAIR(CP_PRIMARY));
  }
  wrefresh(t->header);
}

static void draw_status(tui_t *t) {
  if (!t->status)
    return;
  werase(t->status);
  if (HAS_COLOR())
    wbkgd(t->status, COLOR_PAIR(CP_STATUS));
  const char *msg = t->status_msg[0] ? t->status_msg : "ready";
  char line[600];
  snprintf(line, sizeof(line), " %s", msg);
  draw_ansi_line(t->status, 0, t->cols - 1, line, CP_STATUS, 0, 0);
  wrefresh(t->status);
}

/* Visual position of every byte offset: soft wrap at the window edge plus
 * hard newlines. Calls fn(ud, offset, row, col, wc, width) per character and
 * returns the row count; cursor row/col are reported for t->cur. */
typedef void (*input_cell_fn)(void *ud, int row, int col, wchar_t wc, int cw);

static int input_layout(const tui_t *t, input_cell_fn fn, void *ud,
                        int *cur_row, int *cur_col) {
  int row = 0, col = 3, right = t->cols - 1;
  *cur_row = 0;
  *cur_col = 3;
  size_t i = 0;
  while (i < t->in_len) {
    if (i == t->cur) {
      *cur_row = row;
      *cur_col = col;
    }
    if (t->inbuf[i] == '\n') {
      row++;
      col = 3;
      i++;
      continue;
    }
    wchar_t wc;
    size_t eaten;
    utf8_decode(t->inbuf + i, t->in_len - i, &wc, &eaten);
    if (wc == L'\t')
      wc = L' ';
    int cw = utf8_width(wc);
    if (col + cw > right && col > 3) {
      row++;
      col = 3;
    }
    if (fn)
      fn(ud, row, col, wc, cw);
    col += cw;
    i += eaten;
  }
  if (t->cur >= t->in_len) {
    if (col >= right) {
      row++;
      col = 3;
    }
    *cur_row = row;
    *cur_col = col;
  }
  return row + 1;
}

typedef struct {
  WINDOW *win;
  int top, h, attrs;
} input_draw_t;

static void input_draw_cell(void *ud, int row, int col, wchar_t wc, int cw) {
  (void)cw;
  input_draw_t *d = ud;
  if (row < d->top || row >= d->top + d->h)
    return;
  put_wc(d->win, row - d->top, col, wc, d->attrs);
}

static void draw_input(tui_t *t) {
  if (!t->input)
    return;
  werase(t->input);
  if (HAS_COLOR())
    wbkgd(t->input, COLOR_PAIR(CP_INPUT));
  int h = t->input_rows > 0 ? t->input_rows : 1;
  int cr, cc;
  input_layout(t, NULL, NULL, &cr, &cc);
  int top = cr >= h ? cr - h + 1 : 0;
  for (int r = 0; r < h; r++)
    mvwaddstr(t->input, r, 0,
              r + top == 0 ? (t->busy ? (g_ascii ? " * " : " … ") : " > ")
                           : "   ");
  if (top > 0)
    mvwaddstr(t->input, 0, 0, g_ascii ? " ^ " : " ↑ ");
  if (t->in_len == 0) {
    const char *hint =
        t->busy ? "working… Enter queues a message · Esc cancels"
                : "Ask anything · / commands · @ files · Ctrl+N newline";
    int attrs = A_DIM | (HAS_COLOR() ? (int)COLOR_PAIR(CP_MUTED) : 0);
    wattron(t->input, attrs);
    if (g_ascii)
      hint = t->busy ? "working... Enter queues a message - Esc cancels"
                     : "Ask anything - / commands - @ files - Ctrl+N newline";
    size_t fit = utf8_fit_cols(hint, strlen(hint), t->cols - 5);
    mvwaddnstr(t->input, 0, 3, hint, (int)fit);
    wattroff(t->input, attrs);
    wmove(t->input, 0, 3);
    wrefresh(t->input);
    return;
  }
  input_draw_t d = {t->input, top, h,
                    HAS_COLOR() ? (int)COLOR_PAIR(CP_INPUT) : 0};
  input_layout(t, input_draw_cell, &d, &cr, &cc);
  if (cc >= t->cols)
    cc = t->cols - 1;
  wmove(t->input, cr - top, cc);
  wrefresh(t->input);
}

/* Popup rows at the bottom of the transcript, just above the input. */
static void draw_completion(tui_t *t, int h, int w) {
  t->comp_drawn = t->comp_n;
  if (t->comp_n <= 0 || h < 2)
    return;
  int n = t->comp_n < h - 1 ? t->comp_n : h - 1;
  int bw = w - 2 < 90 ? w - 2 : 90;
  for (int i = 0; i < n; i++) {
    int y = h - n + i;
    const comp_item_t *c = &t->comp[i];
    char line[420];
    snprintf(line, sizeof(line), " %-22s %s", c->text, c->desc);
    int sel = i == t->comp_sel;
    wmove(t->logw, y, 1);
    for (int x = 0; x < bw; x++)
      waddch(t->logw, ' ' | (sel ? A_REVERSE : 0) |
                          (HAS_COLOR() ? COLOR_PAIR(CP_HEADER) : 0));
    if (sel)
      wattron(t->logw, A_REVERSE);
    size_t fit = utf8_fit_cols(line, strlen(line), bw);
    char cut[420];
    snprintf(cut, sizeof(cut), "%.*s", (int)fit, line);
    if (HAS_COLOR())
      wattron(t->logw, COLOR_PAIR(sel ? CP_PRIMARY : CP_HEADER));
    mvwaddstr(t->logw, y, 1, cut);
    if (HAS_COLOR())
      wattroff(t->logw, COLOR_PAIR(sel ? CP_PRIMARY : CP_HEADER));
    if (sel)
      wattroff(t->logw, A_REVERSE);
  }
}

/* Task list panel above the status bar while todo_write has open items. */
static int todo_open_items(const char *todo, int *total) {
  int open = 0, n = 0;
  for (const char *p = todo; p && *p;) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    if (len > 0) {
      n++;
      if (!(len >= 3 && strncmp(p, "[x]", 3) == 0))
        open++;
    }
    p = nl ? nl + 1 : p + len;
  }
  if (total)
    *total = n;
  return open;
}

static void draw_todo(tui_t *t) {
  if (!t->todow)
    return;
  werase(t->todow);
  if (HAS_COLOR())
    wbkgd(t->todow, COLOR_PAIR(CP_PANEL));
  int total = 0, open = todo_open_items(t->todo, &total);
  char head[96];
  snprintf(head, sizeof(head), g_ascii ? " Tasks %d/%d done  (Ctrl+T hides)"
                                       : " Tasks %d/%d done  · Ctrl+T hides",
           total - open, total);
  draw_ansi_line(t->todow, 0, t->cols - 1, head, CP_PRIMARY, 1, 0);
  int row = 1, skipped = 0;
  int room = t->todo_rows - 1;
  /* keep the first unfinished item visible */
  int first_open = 0, idx = 0;
  for (const char *p = t->todo; p && *p; idx++) {
    const char *nl = strchr(p, '\n');
    if (strncmp(p, "[x]", 3) != 0) {
      first_open = idx;
      break;
    }
    p = nl ? nl + 1 : p + strlen(p);
  }
  int skip = first_open > 1 ? first_open - 1 : 0;
  if (total - skip < room)
    skip = total > room ? total - room : 0;
  idx = 0;
  for (const char *p = t->todo; p && *p && row <= room;) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    if (len >= 3 && idx++ >= skip) {
      const char *mark = "○";
      int pair = CP_PANEL, dim = 0;
      if (strncmp(p, "[x]", 3) == 0) {
        mark = "✓";
        pair = CP_SUCCESS;
        dim = 1;
      } else if (strncmp(p, "[~]", 3) == 0) {
        mark = "▸";
        pair = CP_PRIMARY;
      }
      char line[400];
      if (row == room && total - idx > 0) {
        snprintf(line, sizeof(line), "   … %d more", total - idx + 1);
        draw_ansi_line(t->todow, row, t->cols - 1, line, CP_MUTED, 0, 1);
        break;
      }
      const char *txt = p + 3;
      while (txt < p + len && *txt == ' ')
        txt++;
      snprintf(line, sizeof(line), "  %s %.*s", mark, (int)(p + len - txt),
               txt);
      draw_ansi_line(t->todow, row++, t->cols - 1, line, pair, 0, dim);
    } else if (len >= 3) {
      skipped++;
    }
    p = nl ? nl + 1 : p + len;
  }
  (void)skipped;
  wrefresh(t->todow);
}

static void draw_log(tui_t *t) {
  if (!t->logw)
    return;
  werase(t->logw);
  if (HAS_COLOR())
    wbkgd(t->logw, COLOR_PAIR(CP_PANEL));
  int h, w;
  getmaxyx(t->logw, h, w);
  if (h < 1 || w < 1)
    return;

  dlines_t dl = {0};
  build_display(t, &dl, w);
  int total = dl.n > 0 ? dl.n : 1;
  int max_scroll = total - h;
  if (max_scroll < 0)
    max_scroll = 0;
  if (t->log_scroll > max_scroll)
    t->log_scroll = max_scroll;
  if (t->log_scroll < 0)
    t->log_scroll = 0;
  int start = total - h - t->log_scroll;
  if (start < 0)
    start = 0;

  for (int row = 0; row < h; row++) {
    int li = start + row;
    if (li < 0 || li >= dl.n)
      continue;
    dline_t *L = &dl.lines[li];
    draw_ansi_line(t->logw, row, w, L->text, L->pair, L->bold, L->dim);
  }
  if (t->log_scroll > 0 && h > 2) {
    char more[128];
    snprintf(more, sizeof(more),
             g_ascii ? " -- %d more lines below - End/PgDn - %d above -- "
                     : " ── %d more lines below · End/PgDn · %d above ── ",
             t->log_scroll, start);
    wmove(t->logw, h - 1, 0);
    wclrtoeol(t->logw);
    wattron(t->logw, A_REVERSE);
    draw_ansi_line(t->logw, h - 1, w, more, CP_PRIMARY, 1, 0);
    wattroff(t->logw, A_REVERSE);
  }
  dlines_free(&dl);
  draw_completion(t, h, w);
  wrefresh(t->logw);
}

static void redraw_all(tui_t *t) {
  theme_paint_root();
  draw_header(t);
  draw_log(t);
  draw_todo(t);
  draw_status(t);
  draw_input(t);
}

/* --- session reload ------------------------------------------------------- */

static void push_system_line(tui_t *t, const char *fmt, ...) {
  char tmp[1024];
  va_list ap;
  va_start(ap, fmt);
  vsnprintf(tmp, sizeof(tmp), fmt, ap);
  va_end(ap);
  block_t *b = blocks_push(&t->hist);
  if (!b)
    return;
  b->kind = BLK_SYSTEM;
  block_set_body(b, tmp, strlen(tmp));
}

static void print_welcome(tui_t *t) {
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  push_system_line(t, "Welcome to CST-Agent");
  push_system_line(t, "/ for commands (/help lists them) · @ to mention a file "
                      "· Esc cancels a turn · Ctrl+C twice quits");
  if (cfg)
    push_system_line(t, "Model %s @ %s · protocol %s · tools %s", cfg->model,
                     cfg->api_base, cst_protocol_name(cfg->protocol),
                     cst_tool_profile_name(cfg->tool_profile));
  if (cfg && cst_agent_notes(t->agent) && cst_agent_notes(t->agent)[0])
    push_system_line(t, "Project notes loaded from AGENTS.md");
  push_system_line(t, "");
}

typedef struct {
  char id[CTL_MAX_ID];
  char title[160];
} call_title_t;

/* Native tool_calls JSON → per-call one-line titles for replayed cards. */
static void remember_call_titles(const char *json, call_title_t *v, int *n) {
  cJSON *arr = cJSON_Parse(json);
  const cJSON *it;
  cJSON_ArrayForEach(it, arr) {
    const cJSON *id = cJSON_GetObjectItemCaseSensitive(it, "id");
    const cJSON *fn = cJSON_GetObjectItemCaseSensitive(it, "function");
    const cJSON *name = cJSON_GetObjectItemCaseSensitive(fn, "name");
    const cJSON *args = cJSON_GetObjectItemCaseSensitive(fn, "arguments");
    if (!cJSON_IsString(id) || !cJSON_IsString(name))
      continue;
    ctl_tool_call_t c;
    memset(&c, 0, sizeof(c));
    if (cst_tool_call_from_native(&c, id->valuestring, name->valuestring,
                                  cJSON_IsString(args) ? args->valuestring
                                                       : "{}") == 0) {
      int k = *n < 64 ? (*n)++ : 63;
      snprintf(v[k].id, sizeof(v[k].id), "%s", id->valuestring);
      tool_arg_summary(&c, v[k].title, sizeof(v[k].title));
    }
    for (int i = 0; i < c.nargs; i++)
      free(c.args[i].value);
  }
  cJSON_Delete(arr);
}

static void reload_hist_from_session(tui_t *t) {
  live_end_cleanup(t);
  blocks_clear(&t->hist);
  t->log_scroll = 0;
  t->think_idx = -1;
  t->last_tool_idx = -1;
  t->focus_think_idx = -1;

  print_welcome(t);

  cst_session_t *s = cst_agent_session(t->agent);
  if (!s)
    return;
  cst_session_lock(s);
  int n = cst_session_count(s);
  int non_sys = 0;
  for (int i = 0; i < n; i++) {
    const cst_message_t *m = cst_session_get(s, i);
    if (m && m->role != CST_ROLE_SYSTEM)
      non_sys++;
  }
  int skip = non_sys > REPLAY_MSGS ? non_sys - REPLAY_MSGS : 0;
  int seen = 0;
  static call_title_t titles[64];
  int ntitles = 0;
  for (int i = 0; i < n; i++) {
    const cst_message_t *m = cst_session_get(s, i);
    if (!m || m->role == CST_ROLE_SYSTEM)
      continue;
    if (seen++ < skip)
      continue;
    if (m->role == CST_ROLE_ASSISTANT && m->tool_calls_json)
      remember_call_titles(m->tool_calls_json, titles, &ntitles);
    if (m->role == CST_ROLE_ASSISTANT &&
        (!m->content || !m->content[strspn(m->content, " \t\r\n")]))
      continue; /* tool calls only */
    block_t *b = blocks_push(&t->hist);
    if (!b)
      continue;
    if (msg_is_tool_result(m)) {
      b->kind = BLK_TOOL;
      snprintf(b->tool_name, sizeof(b->tool_name), "%s",
               m->tool_name[0] ? m->tool_name : "tool");
      snprintf(b->tool_id, sizeof(b->tool_id), "%s", m->tool_call_id);
      snprintf(b->meta, sizeof(b->meta), "done");
      const char *body;
      size_t blen;
      tool_result_view(m->content, &body, &blen);
      block_set_body(b, body, blen);
      {
        char path[256];
        diff_extract_path(b->body, NULL, path, sizeof(path));
        const char *title = path;
        for (int k = 0; !path[0] && k < ntitles; k++)
          if (strcmp(titles[k].id, m->tool_call_id) == 0)
            title = titles[k].title;
        block_set_title(b, title);
      }
      /* OpenCode: write/edit cards open (still fold at DIFF_FOLD_LINES). */
      if (cst_tool_is_write(b->tool_name))
        b->expanded = 1;
      else
        b->expanded = 0;
      t->last_tool_idx = t->hist.n - 1;
    } else if (m->role == CST_ROLE_USER) {
      b->kind = BLK_USER;
      block_set_title(b, "You");
      block_set_body(b, m->content ? m->content : "",
                     m->content ? strlen(m->content) : 0);
      b->expanded = 1;
    } else if (m->role == CST_ROLE_ASSISTANT) {
      b->kind = BLK_ASSISTANT;
      block_set_title(b, "Assistant");
      if (m->content)
        block_set_body(b, m->content, strlen(m->content));
      b->expanded = 1;
      block_render_assistant(b);
    }
  }
  cst_session_unlock(s);
}

/* --- layout --------------------------------------------------------------- */

static int input_visual_rows(const tui_t *t) {
  int cr, cc;
  int rows = input_layout(t, NULL, NULL, &cr, &cc);
  if (rows < 1)
    rows = 1;
  if (rows > INPUT_MAX_ROWS)
    rows = INPUT_MAX_ROWS;
  return rows;
}

static void layout(tui_t *t) {
  getmaxyx(stdscr, t->rows, t->cols);
  theme_paint_root();
  if (t->header)
    delwin(t->header);
  if (t->logw)
    delwin(t->logw);
  if (t->status)
    delwin(t->status);
  if (t->input)
    delwin(t->input);
  if (t->todow)
    delwin(t->todow);
  t->todow = NULL;

  t->input_rows = input_visual_rows(t);
  int total = 0, open = t->show_todo ? todo_open_items(t->todo, &total) : 0;
  t->todo_rows = open ? 1 + (total < TODO_PANEL_MAX ? total : TODO_PANEL_MAX)
                      : 0;
  if (t->rows < 16)
    t->todo_rows = 0;
  int chrome = 1 + 1 + t->input_rows + t->todo_rows;
  if (chrome >= t->rows)
    chrome = t->rows - 1;
  int log_h = t->rows - chrome;
  if (log_h < 1)
    log_h = 1;

  t->header = newwin(1, t->cols, 0, 0);
  t->logw = newwin(log_h, t->cols, 1, 0);
  if (t->todo_rows)
    t->todow = newwin(t->todo_rows, t->cols, 1 + log_h, 0);
  t->status = newwin(1, t->cols, 1 + log_h + t->todo_rows, 0);
  t->input = newwin(t->input_rows, t->cols, 1 + log_h + t->todo_rows + 1, 0);
  if (HAS_COLOR()) {
    wbkgdset(t->header, COLOR_PAIR(CP_HEADER));
    wbkgdset(t->logw, COLOR_PAIR(CP_PANEL));
    wbkgdset(t->status, COLOR_PAIR(CP_STATUS));
    wbkgdset(t->input, COLOR_PAIR(CP_INPUT));
  }
  scrollok(t->logw, FALSE);
  keypad(t->input, TRUE);
  mousemask(ALL_MOUSE_EVENTS | REPORT_MOUSE_POSITION, NULL);
  mouseinterval(0);
}

static void redraw_all(tui_t *t);
static int start_turn(tui_t *t, char *prompt); /* takes ownership of prompt */

static void layout_maybe_grow_input(tui_t *t) {
  int need = input_visual_rows(t);
  if (need != t->input_rows) {
    layout(t);
    wtimeout(t->input, 80);
    redraw_all(t);
  } else {
    draw_input(t);
  }
}

static void update_completion(tui_t *t);

static void input_changed(tui_t *t) {
  t->hist_browse = -1;
  t->comp_off = 0;
  update_completion(t);
}

static void input_insert(tui_t *t, const char *p, size_t n) {
  if (t->in_len + n >= INPUT_CAP)
    return;
  memmove(t->inbuf + t->cur + n, t->inbuf + t->cur, t->in_len - t->cur);
  memcpy(t->inbuf + t->cur, p, n);
  t->in_len += n;
  t->cur += n;
  t->inbuf[t->in_len] = 0;
  if (!t->in_paste)
    input_changed(t);
}

static void input_erase(tui_t *t, size_t from, size_t to) {
  if (to > t->in_len)
    to = t->in_len;
  if (from >= to)
    return;
  memmove(t->inbuf + from, t->inbuf + to, t->in_len - to);
  t->in_len -= to - from;
  t->inbuf[t->in_len] = 0;
  if (t->cur >= to)
    t->cur -= to - from;
  else if (t->cur > from)
    t->cur = from;
  input_changed(t);
}

static void input_set(tui_t *t, const char *s) {
  snprintf(t->inbuf, sizeof(t->inbuf), "%s", s ? s : "");
  t->in_len = strlen(t->inbuf);
  t->cur = t->in_len;
  input_changed(t);
}

static void input_clear(tui_t *t) { input_set(t, ""); }

static void input_put_wc(tui_t *t, wchar_t wc) {
  char mb[8];
  mbstate_t st;
  memset(&st, 0, sizeof(st));
  size_t n = wcrtomb(mb, wc, &st);
  if (n == (size_t)-1 || n == 0)
    return;
  input_insert(t, mb, n);
}

static void input_put_byte(tui_t *t, char ch) { input_insert(t, &ch, 1); }

static size_t next_len(const tui_t *t, size_t at) {
  if (at >= t->in_len)
    return 0;
  size_t i = at + 1;
  while (i < t->in_len && ((unsigned char)t->inbuf[i] & 0xC0) == 0x80)
    i++;
  return i - at;
}

static size_t line_start(const tui_t *t, size_t at) {
  while (at > 0 && t->inbuf[at - 1] != '\n')
    at--;
  return at;
}

static size_t line_end(const tui_t *t, size_t at) {
  while (at < t->in_len && t->inbuf[at] != '\n')
    at++;
  return at;
}

static int is_word(unsigned char c) { return c >= 0x80 || isalnum(c) || c == '_'; }

static size_t word_left(const tui_t *t, size_t at) {
  while (at > 0 && !is_word((unsigned char)t->inbuf[at - 1]))
    at--;
  while (at > 0 && is_word((unsigned char)t->inbuf[at - 1]))
    at--;
  return at;
}

static size_t word_right(const tui_t *t, size_t at) {
  while (at < t->in_len && !is_word((unsigned char)t->inbuf[at]))
    at++;
  while (at < t->in_len && is_word((unsigned char)t->inbuf[at]))
    at++;
  return at;
}

/* Move to the previous/next logical line keeping the column (in chars).
 * Returns 0 when already on the first/last line. */
static int input_line_move(tui_t *t, int dir) {
  size_t ls = line_start(t, t->cur);
  int col = 0;
  for (size_t i = ls; i < t->cur; i += next_len(t, i))
    col++;
  size_t target;
  if (dir < 0) {
    if (ls == 0)
      return 0;
    target = line_start(t, ls - 1);
  } else {
    size_t le = line_end(t, t->cur);
    if (le >= t->in_len)
      return 0;
    target = le + 1;
  }
  size_t te = line_end(t, target);
  while (col-- > 0 && target < te)
    target += next_len(t, target);
  t->cur = target;
  return 1;
}

static void prompt_hist_push(tui_t *t, const char *prompt) {
  if (!prompt || !prompt[0])
    return;
  if (t->prompt_hist_n >= PROMPT_HIST_CAP) {
    free(t->prompt_hist[0]);
    memmove(t->prompt_hist, t->prompt_hist + 1,
            (PROMPT_HIST_CAP - 1) * sizeof(char *));
    t->prompt_hist_n = PROMPT_HIST_CAP - 1;
  }
  t->prompt_hist[t->prompt_hist_n++] = strdup(prompt);
  t->hist_browse = -1;
}

static void hist_load_into_input(tui_t *t, int idx) {
  if (idx < 0 || idx >= t->prompt_hist_n)
    return;
  input_set(t, t->prompt_hist[idx]);
  t->hist_browse = idx;
}

static int queue_push(tui_t *t, const char *prompt) {
  if (!prompt || !prompt[0])
    return -1;
  if (t->queue_n >= QUEUE_CAP)
    return -1;
  t->queue[t->queue_n] = strdup(prompt);
  if (!t->queue[t->queue_n])
    return -1;
  t->queue_n++;
  return 0;
}

static char *queue_pop(tui_t *t) {
  if (t->queue_n <= 0)
    return NULL;
  char *p = t->queue[0];
  memmove(t->queue, t->queue + 1, (size_t)(t->queue_n - 1) * sizeof(char *));
  t->queue_n--;
  t->queue[t->queue_n] = NULL;
  return p;
}

static void queue_free_all(tui_t *t) {
  for (int i = 0; i < t->queue_n; i++) {
    free(t->queue[i]);
    t->queue[i] = NULL;
  }
  t->queue_n = 0;
}

/* --- hooks (may run on worker thread) ------------------------------------- */

static void on_status(const char *msg, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  set_status_locked(t, msg);
  tui_unlock(t);
}

static void on_assistant_delta(const char *text, size_t len, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  collapse_open_think(t);
  if (!t->as_live)
    live_begin(t);
  live_feed(t, text, len);
  t->log_scroll = 0;
  set_status_locked(t, "streaming…");
  tui_mark_dirty(t);
  tui_unlock(t);
}

static void on_think_delta(const char *text, size_t len, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  if (t->think_idx < 0) {
    block_t *b = blocks_push(&t->hist);
    if (b) {
      b->kind = BLK_THINK;
      block_set_title(b, "Thinking…");
      b->expanded = 1;
      t->think_idx = t->hist.n - 1;
      t->focus_think_idx = t->think_idx;
      clock_gettime(CLOCK_MONOTONIC, &t->think_t0);
      t->think_timing = 1;
    }
  }
  if (t->think_idx >= 0 && t->think_idx < t->hist.n && text && len)
    block_append_body(&t->hist.items[t->think_idx], text, len);
  set_status_locked(t, "thinking…");
  t->log_scroll = 0;
  tui_mark_dirty(t);
  tui_unlock(t);
}

static void on_tool_event(const char *phase, const ctl_tool_call_t *call,
                          const char *detail, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  collapse_open_think(t);
  if (t->as_live &&
      (strcmp(phase, "open") == 0 || strcmp(phase, "ready") == 0))
    live_seal(t);
  if (!call) {
    tui_unlock(t);
    return;
  }

  int idx = find_tool_block(t, call->id);
  block_t *b = NULL;
  if (idx < 0) {
    b = blocks_push(&t->hist);
    if (!b) {
      tui_unlock(t);
      return;
    }
    b->kind = BLK_TOOL;
    snprintf(b->tool_name, sizeof(b->tool_name), "%s", call->name);
    snprintf(b->tool_id, sizeof(b->tool_id), "%s", call->id);
    b->expanded = 0;
    idx = t->hist.n - 1;
  } else {
    b = &t->hist.items[idx];
  }
  t->last_tool_idx = idx;

  char args[160];
  tool_arg_summary(call, args, sizeof(args));
  block_set_title(b, args);

  if (strcmp(phase, "open") == 0) {
    snprintf(b->meta, sizeof(b->meta), "pending");
    set_status_locked(t, "tool pending…");
  } else if (strcmp(phase, "arg") == 0) {
    snprintf(b->meta, sizeof(b->meta), "args…");
  } else if (strcmp(phase, "ready") == 0) {
    snprintf(b->meta, sizeof(b->meta), "ready");
    set_status_locked(t, "tool confirmed");
  } else if (strcmp(phase, "run") == 0) {
    snprintf(b->meta, sizeof(b->meta), "running");
    set_status_locked(t, "running tool…");
  } else if (strcmp(phase, "denied") == 0) {
    snprintf(b->meta, sizeof(b->meta), "denied");
    block_set_body(b, "denied by user", strlen("denied by user"));
    set_status_locked(t, "tool denied");
  } else if (strcmp(phase, "done") == 0) {
    snprintf(b->meta, sizeof(b->meta), "%s", detail ? detail : "done");
    if (!b->body || !b->body[0])
      attach_tool_output_from_session(t, b);
    /* Auto-expand write/patch cards so diffs are visible like OpenCode. */
    if (cst_tool_is_write(call->name))
      b->expanded = 1;
    set_status_locked(t, "tool done");
  }

  t->log_scroll = 0;
  tui_mark_dirty(t);
  tui_unlock(t);
}

static void on_tool_result(const ctl_tool_call_t *call, const char *out,
                           size_t len, int exit_code, void *ud) {
  (void)exit_code;
  tui_t *t = ud;
  if (!call)
    return;
  tui_lock(t);
  int idx = find_tool_block(t, call->id);
  if (idx >= 0) {
    block_t *b = &t->hist.items[idx];
    block_set_body(b, out ? out : "", out ? len : 0);
    char path[256];
    diff_extract_path(b->body, NULL, path, sizeof(path));
    if (path[0])
      block_set_title(b, path);
    tui_mark_dirty(t);
  }
  tui_unlock(t);
}

static int on_permission(const char *tool_name, const char *detail,
                         const char *preview, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  snprintf(t->perm_tool, sizeof(t->perm_tool), "%s",
           tool_name ? tool_name : "tool");
  snprintf(t->perm_detail, sizeof(t->perm_detail), "%s", detail ? detail : "");
  free(t->perm_preview);
  t->perm_preview = preview ? xstrdup(preview) : NULL;
  t->perm_prefix[0] = 0;
  if (preview && strcmp(t->perm_tool, "run_shell") == 0)
    cst_perms_suggest_prefix(preview, t->perm_prefix, sizeof(t->perm_prefix));
  t->perm_scroll = 0;
  t->awaiting_perm = 1;
  t->perm_ans = -1;
  t->perm_ask = 1;
  tui_mark_dirty(t);
  tui_unlock(t);

  for (;;) {
    tui_lock(t);
    int ans = t->perm_ans;
    if (ans >= 0) {
      t->awaiting_perm = 0;
      t->perm_ask = 0;
      free(t->perm_preview);
      t->perm_preview = NULL;
    }
    tui_unlock(t);
    if (ans >= 0)
      return ans;
    usleep(20000);
  }
}

static int on_ask_user(const char *q, const char *opts, char *ans,
                       size_t ans_sz, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  snprintf(t->ask_q, sizeof(t->ask_q), "%s", q ? q : "");
  t->ask_nopts = 0;
  for (const char *p = opts; p && *p && t->ask_nopts < ASK_OPTS_MAX;) {
    const char *nl = strchr(p, '\n');
    size_t len = nl ? (size_t)(nl - p) : strlen(p);
    while (len && (p[len - 1] == '\r' || p[len - 1] == ' '))
      len--;
    if (len)
      snprintf(t->ask_opts[t->ask_nopts++], sizeof(t->ask_opts[0]), "%.*s",
               (int)len, p);
    if (!nl)
      break;
    p = nl + 1;
  }
  t->ask_sel = 0;
  t->ask_buf[0] = 0;
  t->ask_done = 0;
  t->ask_pending = 1;
  tui_mark_dirty(t);
  tui_unlock(t);
  for (;;) {
    tui_lock(t);
    int done = t->ask_done;
    if (done) {
      t->ask_pending = 0;
      t->ask_done = 0;
      snprintf(ans, ans_sz, "%s", t->ask_buf);
    }
    int rc = t->ask_rc;
    tui_unlock(t);
    if (done)
      return rc;
    usleep(20000);
  }
}

static void on_todo(const char *text, void *ud) {
  tui_t *t = ud;
  tui_lock(t);
  free(t->todo);
  t->todo = text && text[0] ? xstrdup(text) : NULL;
  t->need_layout = 1;
  tui_mark_dirty(t);
  tui_unlock(t);
}

/* --- modals drawn over the transcript ------------------------------------- */

static void modal_footer(tui_t *t, int h, int w, const char *keys) {
  wmove(t->logw, h - 1, 0);
  wclrtoeol(t->logw);
  wattron(t->logw, A_REVERSE);
  draw_ansi_line(t->logw, h - 1, w, keys, CP_PRIMARY, 1, 0);
  wattroff(t->logw, A_REVERSE);
}

static void draw_perm_modal(tui_t *t) {
  int h, w;
  getmaxyx(t->logw, h, w);
  werase(t->logw);
  if (HAS_COLOR())
    wbkgd(t->logw, COLOR_PAIR(CP_PANEL));
  dlines_t dl = {0};
  char head[700];
  snprintf(head, sizeof(head), "Allow %s?", t->perm_tool);
  dlines_push(&dl, head, CP_PRIMARY, 1, 0);
  int is_shell = strcmp(t->perm_tool, "run_shell") == 0;
  if (is_shell && t->perm_preview) {
    push_wrapped(&dl, "  $ ", t->perm_preview, w, CP_TOOL, 1, 0, 0);
  } else {
    push_wrapped(&dl, "  ", t->perm_detail, w, CP_MUTED, 0, 0, 0);
    if (t->perm_preview && t->perm_preview[0]) {
      dlines_push(&dl, "", 0, 0, 0);
      push_diff_or_body(&dl, t->perm_preview, w, CP_MUTED, 1, 100000, 1);
    }
  }
  int body_h = h - 1;
  int max_scroll = dl.n > body_h ? dl.n - body_h : 0;
  if (t->perm_scroll > max_scroll)
    t->perm_scroll = max_scroll;
  if (t->perm_scroll < 0)
    t->perm_scroll = 0;
  for (int r = 0; r < body_h && t->perm_scroll + r < dl.n; r++) {
    dline_t *L = &dl.lines[t->perm_scroll + r];
    draw_ansi_line(t->logw, r, w, L->text, L->pair, L->bold, L->dim);
  }
  char keys[400];
  int k = snprintf(keys, sizeof(keys), " [y] allow once  [a] always allow %s",
                   t->perm_tool);
  if (t->perm_prefix[0])
    k += snprintf(keys + k, sizeof(keys) - (size_t)k,
                  "  [p] always allow `%.60s …`", t->perm_prefix);
  snprintf(keys + k, sizeof(keys) - (size_t)k, "  [n/Esc] deny%s",
           max_scroll ? "  ↑↓ scroll" : "");
  modal_footer(t, h, w, keys);
  dlines_free(&dl);
  wrefresh(t->logw);
}

static void draw_ask_modal(tui_t *t) {
  int h, w;
  getmaxyx(t->logw, h, w);
  werase(t->logw);
  if (HAS_COLOR())
    wbkgd(t->logw, COLOR_PAIR(CP_PANEL));
  dlines_t dl = {0};
  dlines_push(&dl, "The agent asks:", CP_PRIMARY, 1, 0);
  push_wrapped(&dl, "  ", t->ask_q, w, CP_PANEL, 1, 0, 0);
  dlines_push(&dl, "", 0, 0, 0);
  for (int i = 0; i < t->ask_nopts; i++) {
    char line[320];
    snprintf(line, sizeof(line), "%s %d. %s",
             i == t->ask_sel && !t->ask_buf[0] ? (g_ascii ? ">" : "▶") : " ",
             i + 1, t->ask_opts[i]);
    dlines_push(&dl, line, i == t->ask_sel ? CP_PRIMARY : CP_PANEL,
                i == t->ask_sel, 0);
  }
  if (t->ask_nopts)
    dlines_push(&dl, "", 0, 0, 0);
  char typed[1100];
  snprintf(typed, sizeof(typed), "  answer: %s_", t->ask_buf);
  dlines_push(&dl, typed, CP_ASSIST, 0, 0);
  int start = dl.n > h - 1 ? dl.n - (h - 1) : 0;
  for (int r = 0; r < h - 1 && start + r < dl.n; r++) {
    dline_t *L = &dl.lines[start + r];
    draw_ansi_line(t->logw, r, w, L->text, L->pair, L->bold, L->dim);
  }
  modal_footer(t, h, w,
               t->ask_nopts ? " ↑↓/1-9 pick · type your own answer · Enter "
                              "send · Esc dismiss"
                            : " type your answer · Enter send · Esc dismiss");
  dlines_free(&dl);
  wrefresh(t->logw);
}

/* --- modal picker (↑↓ Enter Esc) ------------------------------------------ */

/* items: n rows of labels (each ≤127 chars). Returns index or -1. */
static int picker_run(tui_t *t, const char *title, char items[][128], int n,
                      int cur_idx) {
  if (n <= 0)
    return -1;
  if (cur_idx < 0 || cur_idx >= n)
    cur_idx = 0;

  int sel = cur_idx;
  int top = 0;
  wtimeout(stdscr, -1);
  keypad(stdscr, TRUE);
  curs_set(0);

  for (;;) {
    int rows, cols;
    getmaxyx(stdscr, rows, cols);
    int box_h = rows > 4 ? rows - 2 : rows;
    if (box_h > n + 2)
      box_h = n + 2;
    if (box_h < 3)
      box_h = rows > 0 ? rows : 3;
    int visible = box_h - 2;
    if (visible < 1)
      visible = 1;
    if (sel < top)
      top = sel;
    if (sel >= top + visible)
      top = sel - visible + 1;

    werase(stdscr);
    if (HAS_COLOR())
      wbkgd(stdscr, COLOR_PAIR(CP_PANEL));
    mvprintw(0, 1, "%s  (↑↓ Enter · Esc cancel)", title ? title : "Select");
    for (int i = 0; i < visible && top + i < n; i++) {
      int idx = top + i;
      int y = 1 + i;
      if (idx == sel) {
        if (HAS_COLOR())
          attron(COLOR_PAIR(CP_PRIMARY) | A_BOLD);
        else
          attron(A_REVERSE);
      } else if (HAS_COLOR()) {
        attron(COLOR_PAIR(CP_MUTED));
      }
      mvprintw(y, 2, "%s %.*s", idx == cur_idx ? "*" : " ", cols - 6,
               items[idx]);
      if (idx == sel) {
        if (HAS_COLOR())
          attroff(COLOR_PAIR(CP_PRIMARY) | A_BOLD);
        else
          attroff(A_REVERSE);
      } else if (HAS_COLOR()) {
        attroff(COLOR_PAIR(CP_MUTED));
      }
    }
    refresh();

    wint_t wch = 0;
    int rc = get_wch(&wch);
    if (rc == ERR)
      continue;
    if (rc == KEY_CODE_YES) {
      if (wch == KEY_UP) {
        if (sel > 0)
          sel--;
        continue;
      }
      if (wch == KEY_DOWN) {
        if (sel + 1 < n)
          sel++;
        continue;
      }
      if (wch == KEY_RESIZE)
        continue;
      if (wch == KEY_ENTER)
        break;
      continue;
    }
    if (wch == 10 || wch == 13) /* LF/CR */
      break;
    if (wch == 27) { /* Esc */
      sel = -1;
      break;
    }
  }

  curs_set(1);
  layout(t);
  wtimeout(t->input, 80);
  keypad(t->input, TRUE);
  redraw_all(t);
  return sel;
}

/* Full-screen hidden input (API keys). Returns 0 with out filled, -1 on
 * Esc / Ctrl+C. */
static int secret_input_run(tui_t *t, const char *title, const char *hint,
                            char *out, size_t n) {
  size_t len = 0;
  out[0] = 0;
  int rc = -1;
  wtimeout(stdscr, -1);
  keypad(stdscr, TRUE);
  curs_set(1);
  for (;;) {
    int rows, cols;
    getmaxyx(stdscr, rows, cols);
    (void)rows;
    werase(stdscr);
    if (HAS_COLOR())
      wbkgd(stdscr, COLOR_PAIR(CP_PANEL));
    if (HAS_COLOR())
      attron(COLOR_PAIR(CP_PRIMARY) | A_BOLD);
    mvprintw(1, 2, "%.*s", cols - 4, title);
    if (HAS_COLOR())
      attroff(COLOR_PAIR(CP_PRIMARY) | A_BOLD);
    if (HAS_COLOR())
      attron(COLOR_PAIR(CP_MUTED));
    mvprintw(2, 2, "%.*s", cols - 4, hint);
    mvprintw(6, 2, "%.*s", cols - 4,
             "Enter save · Esc cancel · Ctrl+U clear · paste works");
    if (HAS_COLOR())
      attroff(COLOR_PAIR(CP_MUTED));
    int room = cols - 12 > 1 ? cols - 12 : 1;
    int shown = (int)len < room ? (int)len : room;
    mvprintw(4, 2, "key: ");
    for (int i = 0; i < shown; i++)
      addch('*');
    if ((int)len > shown)
      addstr("…");
    move(4, 7 + shown);
    refresh();

    wint_t wch = 0;
    int r = get_wch(&wch);
    if (r == ERR)
      continue;
    if (r == KEY_CODE_YES) {
      if (wch == KEY_BACKSPACE && len > 0)
        out[--len] = 0;
      else if (wch == KEY_ENTER && len > 0) {
        rc = 0;
        break;
      }
      continue;
    }
    if (wch == 10 || wch == 13) {
      if (len > 0) {
        rc = 0;
        break;
      }
      continue;
    }
    if (wch == 27 || wch == 3)
      break;
    if (wch == 127 || wch == 8) {
      if (len > 0)
        out[--len] = 0;
      continue;
    }
    if (wch == 21) {
      len = 0;
      out[0] = 0;
      continue;
    }
    if (wch > 32 && wch < 127 && len + 1 < n) {
      out[len++] = (char)wch;
      out[len] = 0;
    }
  }
  if (rc != 0)
    memset(out, 0, n);
  layout(t);
  wtimeout(t->input, 80);
  keypad(t->input, TRUE);
  redraw_all(t);
  return rc;
}

/* Saved / env key for the provider, else ask for one and save it. */
static int obtain_key(tui_t *t, const char *provider, char *out, size_t n,
                      int force_ask) {
  if (!force_ask && cst_creds_resolve(provider, out, n, NULL) == 0)
    return 0;
  const cst_provider_t *p = cst_provider_find(provider);
  char dir[1024] = "the config directory";
  os_config_dir(dir, sizeof(dir));
  char title[128], hint[1300];
  snprintf(title, sizeof(title), "API key for %s", provider);
  snprintf(hint, sizeof(hint), "%s · saved to %s/credentials (only you can "
                               "read it)",
           p ? p->api_base : "", dir);
  if (secret_input_run(t, title, hint, out, n) != 0)
    return -1;
  if (cst_creds_save(provider, out) != 0)
    push_system_line(t, "warning: could not save the key; it is used for "
                        "this run only");
  else
    push_system_line(t, "(saved the %s API key)", provider);
  return 0;
}

/* --- slash commands ------------------------------------------------------- */

static void refresh_title(tui_t *t) {
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  char sid[128];
  cst_agent_session_id(t->agent, sid, sizeof(sid));
  cst_session_info_t in;
  t->title[0] = 0;
  if (cfg && cst_agent_store_info(cfg->workspace_root, sid, &in) == 0)
    snprintf(t->title, sizeof(t->title), "%s",
             in.title[0] ? in.title : in.first_user);
  if (!t->title[0])
    snprintf(t->title, sizeof(t->title), "%.8s", sid);
}

static void refresh_todo(tui_t *t) {
  const char *td = cst_agent_todo(t->agent);
  tui_lock(t);
  free(t->todo);
  t->todo = td && td[0] ? xstrdup(td) : NULL;
  t->need_layout = 1;
  tui_unlock(t);
}

static void push_lines(tui_t *t, const char *prefix, const char *text) {
  for (const char *p = text; p && *p;) {
    const char *nl = strchr(p, '\n');
    int len = nl ? (int)(nl - p) : (int)strlen(p);
    push_system_line(t, "%s%.*s", prefix, len > 900 ? 900 : len, p);
    if (!nl)
      break;
    p = nl + 1;
  }
}

static void after_session_change(tui_t *t, const char *note) {
  reload_hist_from_session(t);
  refresh_title(t);
  refresh_todo(t);
  if (note)
    push_system_line(t, "%s", note);
  status_idle(t);
}

typedef struct slash_cmd slash_cmd_t;
typedef void (*slash_fn)(tui_t *t, char *arg, int *quit);
struct slash_cmd {
  const char *name;
  const char *aliases; /* space separated */
  const char *args;
  const char *desc;
  int busy_ok;
  slash_fn fn;
};

static const slash_cmd_t *slash_table(int *n);

static void cmd_help(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  int n;
  const slash_cmd_t *c = slash_table(&n);
  push_system_line(t, "");
  push_system_line(t, "Commands:");
  for (int i = 0; i < n; i++) {
    char name[64];
    snprintf(name, sizeof(name), "/%s %s", c[i].name, c[i].args);
    char also[64] = "";
    if (c[i].aliases[0])
      snprintf(also, sizeof(also), "  (also: %s)", c[i].aliases);
    push_system_line(t, "  %-26s %s%s", name, c[i].desc, also);
  }
  push_system_line(t, "Keys:");
  push_system_line(t, "  Enter send · Ctrl+N / Alt+Enter newline · paste keeps "
                      "newlines");
  push_system_line(t, "  ←→ Home End Ctrl+A/E move · Ctrl+W/U/K delete word/"
                      "to start/to end · Delete");
  push_system_line(t, "  ↑↓ history (or lines) · Tab complete / toggle thought "
                      "· Ctrl+O last tool · Ctrl+T tasks");
  push_system_line(t, "  PgUp/PgDn wheel scroll · Esc cancel turn · Ctrl+C "
                      "twice or Ctrl+D quit");
  push_system_line(t, "");
}

static void cmd_new(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  char id[128] = {0};
  if (cst_agent_new_session(t->agent, id, sizeof(id)) != 0) {
    push_system_line(t, "Error: failed to create session");
    return;
  }
  char note[192];
  snprintf(note, sizeof(note), "(new session %s)", id);
  after_session_change(t, note);
}

static int session_labels(tui_t *t, char ids[][128], char labels[][128],
                          int max) {
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  int n = cst_agent_store_list(cfg->workspace_root, ids, max);
  for (int i = 0; i < n; i++) {
    cst_session_info_t in;
    char when[24] = "?";
    if (cst_agent_store_info(cfg->workspace_root, ids[i], &in) == 0) {
      time_t tt = (time_t)in.mtime;
      struct tm tm;
      os_localtime(&tt, &tm);
      strftime(when, sizeof(when), "%m-%d %H:%M", &tm);
      snprintf(labels[i], 128, "%s  %3d msgs  %.60s", when, in.messages,
               in.title[0] ? in.title : in.first_user);
    } else {
      snprintf(labels[i], 128, "%s", ids[i]);
    }
  }
  return n;
}

static int picker_run(tui_t *t, const char *title, char items[][128], int n,
                      int cur_idx);

static void cmd_session(tui_t *t, char *arg, int *quit) {
  (void)quit;
  static char ids[64][128], labels[64][128];
  char chosen[128];
  if (arg && arg[0]) {
    snprintf(chosen, sizeof(chosen), "%s", arg);
  } else {
    int n = session_labels(t, ids, labels, 64);
    if (n <= 0) {
      push_system_line(t, "Sessions: (none)");
      return;
    }
    char cur[128];
    cst_agent_session_id(t->agent, cur, sizeof(cur));
    int cur_idx = 0;
    for (int i = 0; i < n; i++)
      if (strcmp(ids[i], cur) == 0)
        cur_idx = i;
    int pick = picker_run(t, "Session", labels, n, cur_idx);
    if (pick < 0)
      return;
    snprintf(chosen, sizeof(chosen), "%s", ids[pick]);
  }
  if (cst_agent_switch_session(t->agent, chosen) != 0) {
    push_system_line(t, "Error: cannot switch to session '%s'", chosen);
    return;
  }
  char note[192];
  snprintf(note, sizeof(note), "(switched to %s)", chosen);
  after_session_change(t, note);
}

static void cmd_rename(tui_t *t, char *arg, int *quit) {
  (void)quit;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  char sid[128];
  cst_agent_session_id(t->agent, sid, sizeof(sid));
  if (cst_agent_store_title_set(cfg->workspace_root, sid, arg) != 0) {
    push_system_line(t, "Error: cannot set the title");
    return;
  }
  refresh_title(t);
  push_system_line(t, arg && arg[0] ? "(session renamed to \"%s\")"
                                    : "(session title cleared%s)",
                   arg ? arg : "");
}

static void cmd_delete(tui_t *t, char *arg, int *quit) {
  (void)quit;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  static char ids[64][128], labels[64][128];
  char victim[128];
  if (arg && arg[0]) {
    snprintf(victim, sizeof(victim), "%s", arg);
  } else {
    int n = session_labels(t, ids, labels, 64);
    if (n <= 0)
      return;
    int pick = picker_run(t, "Delete which session?", labels, n, 0);
    if (pick < 0)
      return;
    snprintf(victim, sizeof(victim), "%s", ids[pick]);
  }
  char confirm[2][128];
  snprintf(confirm[0], 128, "No, keep it");
  snprintf(confirm[1], 128, "Yes, delete %.100s", victim);
  if (picker_run(t, "Delete session permanently?", confirm, 2, 0) != 1)
    return;
  char cur[128];
  cst_agent_session_id(t->agent, cur, sizeof(cur));
  int was_current = strcmp(cur, victim) == 0;
  if (was_current) {
    char id[128];
    if (cst_agent_new_session(t->agent, id, sizeof(id)) != 0) {
      push_system_line(t, "Error: cannot open a new session first");
      return;
    }
  }
  if (cst_agent_store_delete(cfg->workspace_root, victim) != 0)
    push_system_line(t, "Error: cannot delete %s", victim);
  if (was_current)
    after_session_change(t, NULL);
  push_system_line(t, "(deleted session %s)", victim);
}

static void cmd_model(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  if (!arg || !arg[0]) {
    char models[32][128];
    int n = cst_models_list(cfg->model, models, 32);
    int cur_idx = 0;
    for (int i = 0; i < n; i++)
      if (strcmp(models[i], cfg->model) == 0)
        cur_idx = i;
    int pick = picker_run(t, "Model", models, n, cur_idx);
    if (pick < 0)
      return;
    arg = models[pick];
    snprintf(cfg->model, sizeof(cfg->model), "%s", arg);
  } else {
    snprintf(cfg->model, sizeof(cfg->model), "%.127s", arg);
  }
  cst_settings_remember(cfg);
  push_system_line(t, "(model → %s, context %ld tokens)", cfg->model,
                   cst_model_context_tokens(cfg->model));
}

static void cmd_key(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  char key[512];
  if (obtain_key(t, cfg->provider, key, sizeof(key), 1) != 0) {
    push_system_line(t, "(API key unchanged)");
    return;
  }
  snprintf(cfg->api_key, sizeof(cfg->api_key), "%s", key);
  memset(key, 0, sizeof(key));
}

static void cmd_effort(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  static const char *const names[] = {"low", "medium", "high", "max"};
  static const char *const desc[] = {"quick answers, little thinking",
                                     "balanced (default)",
                                     "thinks longer on hard problems",
                                     "maximum thinking, slowest"};
  const char *want = NULL;
  if (arg && arg[0]) {
    if (!cst_effort_valid(arg)) {
      push_system_line(t, "Unknown effort '%s' (low medium high max)", arg);
      return;
    }
    want = arg;
  } else {
    char items[4][128];
    int cur_idx = 1;
    for (int i = 0; i < 4; i++) {
      snprintf(items[i], 128, "%-7s %s", names[i], desc[i]);
      if (strcmp(names[i], cfg->effort) == 0)
        cur_idx = i;
    }
    int pick = picker_run(t, "Reasoning effort", items, 4, cur_idx);
    if (pick < 0)
      return;
    want = names[pick];
  }
  snprintf(cfg->effort, sizeof(cfg->effort), "%s", want);
  cst_settings_remember(cfg);
  if (cst_effort_wire(cfg->provider, cfg->model, cfg->effort))
    push_system_line(t, "(effort → %s)", cfg->effort);
  else
    push_system_line(t, "(effort → %s; %s/%s does not take an effort "
                        "setting, it applies to DeepSeek and OpenAI "
                        "reasoning models)",
                     cfg->effort, cfg->provider, cfg->model);
}

static void cmd_provider(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  const cst_provider_t *p = NULL;
  if (arg && arg[0]) {
    p = cst_provider_find(arg);
    if (!p) {
      push_system_line(t, "Unknown provider '%s'", arg);
      return;
    }
  } else {
    int n = cst_provider_count();
    char items[16][128];
    int cur_idx = 0;
    for (int i = 0; i < n && i < 16; i++) {
      const cst_provider_t *q = cst_provider_at(i);
      snprintf(items[i], 128, "%-9s %s  (%s)", q->name, q->api_base, q->model);
      if (strcmp(q->name, cfg->provider) == 0)
        cur_idx = i;
    }
    int pick = picker_run(t, "Provider", items, n < 16 ? n : 16, cur_idx);
    if (pick < 0)
      return;
    p = cst_provider_at(pick);
  }
  char key[512];
  if (obtain_key(t, p->name, key, sizeof(key), 0) != 0) {
    push_system_line(t, "(provider unchanged: %s needs an API key)", p->name);
    return;
  }
  cst_settings_t s;
  cst_settings_load(&s);
  const char *model = cst_settings_model(&s, p->name);
  snprintf(cfg->provider, sizeof(cfg->provider), "%s", p->name);
  snprintf(cfg->api_base, sizeof(cfg->api_base), "%s", p->api_base);
  snprintf(cfg->model, sizeof(cfg->model), "%s", model ? model : p->model);
  snprintf(cfg->api_key, sizeof(cfg->api_key), "%s", key);
  memset(key, 0, sizeof(key));
  cst_settings_remember(cfg);
  push_system_line(t, "(provider → %s · %s · model %s)", p->name, p->api_base,
                   cfg->model);
}

static void cmd_protocol(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  cst_protocol_t p = cfg->protocol;
  if (arg && arg[0]) {
    if (cst_protocol_parse(arg, &p) != 0) {
      push_system_line(t, "Unknown protocol '%s' (native-eos native-inc ctl "
                          "ctl-heredoc xml)", arg);
      return;
    }
  } else {
    static const cst_protocol_t all[] = {CST_PROTO_NATIVE_EOS,
                                         CST_PROTO_NATIVE_INC, CST_PROTO_CTL,
                                         CST_PROTO_CTL_HEREDOC, CST_PROTO_XML};
    char names[5][128];
    int cur_idx = 0;
    for (int i = 0; i < 5; i++) {
      snprintf(names[i], sizeof(names[i]), "%s", cst_protocol_name(all[i]));
      if (all[i] == cfg->protocol)
        cur_idx = i;
    }
    int pick = picker_run(t, "Protocol", names, 5, cur_idx);
    if (pick < 0)
      return;
    p = all[pick];
  }
  cfg->protocol = p;
  push_system_line(t, "(protocol → %s)", cst_protocol_name(p));
}

static void cmd_tools(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  if (arg && arg[0]) {
    char verb[16] = "", name[64] = "";
    sscanf(arg, "%15s %63s", verb, name);
    int prof;
    if (cst_tool_profile_parse(verb, &prof) == 0) {
      cfg->tool_profile = prof;
      push_system_line(t, "(tool profile → %s)", cst_tool_profile_name(prof));
    } else if ((strcmp(verb, "on") == 0 || strcmp(verb, "off") == 0) &&
               name[0]) {
      int idx = cst_tool_index(name);
      if (idx < 0) {
        push_system_line(t, "Unknown tool '%s'", name);
        return;
      }
      if (verb[1] == 'n')
        cfg->tools_off &= ~(1ULL << idx);
      else
        cfg->tools_off |= 1ULL << idx;
      push_system_line(t, "(%s %s)", name, verb);
    } else {
      push_system_line(t, "Usage: /tools [on NAME | off NAME | default | "
                          "minimal]");
      return;
    }
  }
  static const char *const perm_names[] = {"read", "write", "shell",
                                           "net",  "ask",   "meta"};
  push_system_line(t, "Tools (profile %s):",
                   cst_tool_profile_name(cfg->tool_profile));
  for (int i = 0; i < cst_tool_count(); i++) {
    const cst_tool_def_t *d = cst_tool_at(i);
    int on = cst_tool_active(cfg, d);
    const char *desc = d->desc ? d->desc : "";
    int dl = (int)strcspn(desc, ".\n");
    push_system_line(t, "  %s %-12s %-5s %.*s", on ? "[x]" : "[ ]", d->name,
                     (int)d->perm < 6 ? perm_names[d->perm] : "?",
                     dl > 70 ? 70 : dl, desc);
  }
}

static void cmd_permissions(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_perms_t *p = cst_agent_perms(t->agent);
  if (arg && strcmp(arg, "reset") == 0) {
    cst_perms_reset(p);
    push_system_line(t, "(saved permission rules cleared)");
    return;
  }
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  push_system_line(t, "Confirmation: shell %s · write %s · net %s%s",
                   cfg->confirm_shell ? "ask" : "auto",
                   cfg->confirm_write ? "ask" : "auto",
                   cfg->confirm_net ? "ask" : "auto",
                   cfg->auto_approve ? " · YOLO (everything auto)" : "");
  char *d = cst_perms_describe(p);
  push_lines(t, "  ", d ? d : "(no saved rules)");
  free(d);
  push_system_line(t, "  saved in .agent/permissions.json · /permissions reset");
}

static void cmd_yolo(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  cfg->auto_approve = !cfg->auto_approve;
  push_system_line(t, cfg->auto_approve
                          ? "(YOLO on: shell, writes and web run without asking)"
                          : "(YOLO off: risky tools ask again)");
}

static void cmd_max_steps(tui_t *t, char *arg, int *quit) {
  (void)quit;
  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  if (arg && atoi(arg) > 0)
    cfg->max_steps = atoi(arg);
  push_system_line(t, "(max steps per turn: %d)", cfg->max_steps);
}

static void cmd_status(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  char sid[128];
  cst_agent_session_id(t->agent, sid, sizeof(sid));
  long win = cst_model_context_tokens(cfg->model);
  long used = cst_agent_last_prompt_tokens(t->agent);
  cst_session_t *s = cst_agent_session(t->agent);
  int nmsg = 0;
  if (s) {
    cst_session_lock(s);
    nmsg = cst_session_count(s);
    cst_session_unlock(s);
  }
  push_system_line(t, "Status:");
  push_system_line(t, "  workspace  %s", cfg->workspace_root);
  push_system_line(t, "  session    %s  (%d messages) %s", sid, nmsg, t->title);
  push_system_line(t, "  provider   %s  %s", cfg->provider, cfg->api_base);
  push_system_line(t, "  model      %s  context %ld/%ld tokens (%ld%%)",
                   cfg->model, used, win, win ? used * 100 / win : 0);
  push_system_line(t, "  effort     %s%s", cfg->effort,
                   cst_effort_wire(cfg->provider, cfg->model, cfg->effort)
                       ? ""
                       : "  (not used by this model)");
  char key[512];
  const char *from = NULL;
  int have = cst_creds_resolve(cfg->provider, key, sizeof(key), &from) == 0;
  int same = have && strcmp(key, cfg->api_key) == 0;
  memset(key, 0, sizeof(key));
  push_system_line(t, "  api key    %s",
                   !cfg->api_key[0] ? "missing — /key to enter one"
                   : !same          ? "this run only (--api-key / CST_API_KEY)"
                   : strcmp(from, "saved") == 0 ? "saved (/key to replace)"
                                                : from);
  push_system_line(t, "  protocol   %s · tools %s · max steps %d",
                   cst_protocol_name(cfg->protocol),
                   cst_tool_profile_name(cfg->tool_profile), cfg->max_steps);
  push_system_line(t, "  approval   %s",
                   cfg->auto_approve ? "YOLO (no confirmation)"
                                     : "asks for shell / writes / web");
  const char *notes = cst_agent_notes(t->agent);
  push_system_line(t, "  notes      %s",
                   notes && notes[0] ? "AGENTS.md loaded" : "(no AGENTS.md)");
  push_system_line(t, "  undo       %d turn(s) can be undone",
                   cst_agent_undo_available(t->agent));
}

static void cmd_todo(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  tui_lock(t);
  char *td = t->todo ? xstrdup(t->todo) : NULL;
  tui_unlock(t);
  push_system_line(t, "Tasks:");
  push_lines(t, "  ", td && td[0] ? td : "(no tasks yet)");
  free(td);
}

static void cmd_undo(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  char rep[4096];
  int rc = cst_agent_undo(t->agent, rep, sizeof(rep));
  push_system_line(t, rc == 0 ? "Undo:" : "Undo failed:");
  push_lines(t, "  ", rep);
}

static void cmd_retry(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  char *p = cst_agent_rewind_last_turn(t->agent);
  if (!p) {
    push_system_line(t, "Nothing to retry");
    return;
  }
  reload_hist_from_session(t);
  push_system_line(t, "(retrying the last prompt; file changes were kept — "
                      "/undo first to revert them)");
  free(t->pending_prompt);
  t->pending_prompt = p;
}

static void cmd_diff(tui_t *t, char *arg, int *quit) {
  (void)quit;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  os_run_result_t st = {0}, df = {0};
  if (os_run_shell_c(cfg->workspace_root, "git status --short", 64 * 1024,
                     &st) != 0 ||
      st.exit_code != 0) {
    push_system_line(t, "/diff needs a git repository");
    free(st.out);
    return;
  }
  char cmd[512];
  snprintf(cmd, sizeof(cmd), "git --no-pager diff --no-color %s%s",
           arg && arg[0] ? "-- " : "", arg ? arg : "");
  os_run_shell_c(cfg->workspace_root, cmd, 512 * 1024, &df);
  push_system_line(t, "git status:");
  push_lines(t, "  ", st.out && st.out[0] ? st.out : "(clean)");
  if (df.out && df.out[0]) {
    block_t *b = blocks_push(&t->hist);
    if (b) {
      b->kind = BLK_TOOL;
      snprintf(b->tool_name, sizeof(b->tool_name), "diff");
      block_set_title(b, "git diff");
      block_set_body(b, df.out, df.out_len);
      snprintf(b->meta, sizeof(b->meta), "done");
      b->expanded = 1;
    }
  }
  free(st.out);
  free(df.out);
}

static void md_fence(FILE *fp, const char *s, size_t max) {
  size_t n = strlen(s);
  fprintf(fp, "````\n%.*s%s\n````\n\n", (int)(n > max ? max : n), s,
          n > max ? "\n…(truncated)" : "");
}

static void cmd_export(tui_t *t, char *arg, int *quit) {
  (void)quit;
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  char sid[128], path[OS_PATH_MAX + 256];
  cst_agent_session_id(t->agent, sid, sizeof(sid));
  if (arg && arg[0] == '/')
    snprintf(path, sizeof(path), "%s", arg);
  else if (arg && arg[0])
    snprintf(path, sizeof(path), "%s/%s", cfg->workspace_root, arg);
  else
    snprintf(path, sizeof(path), "%s/.agent/exports/%s.md", cfg->workspace_root,
             sid);
  char dir[sizeof(path)];
  snprintf(dir, sizeof(dir), "%s", path);
  char *sl = strrchr(dir, '/');
  if (sl) {
    *sl = 0;
    os_mkdir_p(dir, 0755);
  }
  FILE *fp = fopen(path, "w");
  if (!fp) {
    push_system_line(t, "Error: cannot write %s", path);
    return;
  }
  fprintf(fp, "# %s\n\nsession `%s` · model `%s`\n\n", t->title, sid,
          cfg->model);
  cst_session_t *s = cst_agent_session(t->agent);
  cst_session_lock(s);
  for (int i = 0; i < cst_session_count(s); i++) {
    const cst_message_t *m = cst_session_get(s, i);
    const char *c = m->content ? m->content : "";
    if (m->role == CST_ROLE_SYSTEM)
      continue;
    if (msg_is_tool_result(m)) {
      fprintf(fp, "**Tool result** `%s`\n\n", m->tool_name);
      md_fence(fp, c, 4000);
    } else if (m->role == CST_ROLE_USER) {
      fprintf(fp, "## User\n\n%s\n\n", c);
    } else {
      fprintf(fp, "## Assistant\n\n%s\n\n", c);
      if (m->tool_calls_json && m->tool_calls_json[0]) {
        fprintf(fp, "**Tool calls**\n\n");
        md_fence(fp, m->tool_calls_json, 4000);
      }
    }
  }
  cst_session_unlock(s);
  fclose(fp);
  push_system_line(t, "(exported to %s)", path);
}

static void cmd_copy(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  const char *text = NULL;
  for (int i = t->hist.n - 1; i >= 0 && !text; i--)
    if (t->hist.items[i].kind == BLK_ASSISTANT && t->hist.items[i].body)
      text = t->hist.items[i].body;
  if (!text || !text[0]) {
    push_system_line(t, "Nothing to copy yet");
    return;
  }
  static const char b64[] =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  size_t n = strlen(text);
  if (n > 75000)
    n = 75000; /* many terminals cap OSC 52 near 100 KB */
  char *enc = malloc((n + 2) / 3 * 4 + 1);
  if (!enc)
    return;
  size_t o = 0;
  for (size_t i = 0; i < n; i += 3) {
    unsigned v = (unsigned char)text[i] << 16;
    if (i + 1 < n)
      v |= (unsigned char)text[i + 1] << 8;
    if (i + 2 < n)
      v |= (unsigned char)text[i + 2];
    enc[o++] = b64[(v >> 18) & 63];
    enc[o++] = b64[(v >> 12) & 63];
    enc[o++] = i + 1 < n ? b64[(v >> 6) & 63] : '=';
    enc[o++] = i + 2 < n ? b64[v & 63] : '=';
  }
  enc[o] = 0;
  if (getenv("TMUX"))
    printf("\033Ptmux;\033\033]52;c;%s\a\033\\", enc);
  else
    printf("\033]52;c;%s\a", enc);
  fflush(stdout);
  free(enc);
  push_system_line(t, "(copied %zu bytes of the last reply via OSC 52 — the "
                      "terminal must allow clipboard access)", n);
}

static void cmd_init(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  free(t->pending_prompt);
  t->pending_prompt = xstrdup(
      "Analyze this repository and write an AGENTS.md file at the workspace "
      "root for future coding agents. Cover: what the project is, how to "
      "build, test and run it (exact commands), the directory layout, coding "
      "conventions you can infer from the code, and anything surprising. "
      "Explore with list_dir/glob/grep/read_file before writing. Keep it "
      "under 150 lines. If AGENTS.md already exists, improve it rather than "
      "starting over.");
}

static void cmd_compact(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  char err[512] = {0};
  set_status(t, "compacting…");
  redraw_all(t);
  if (cst_agent_compact(t->agent, err, sizeof(err)) != 0) {
    push_system_line(t, "Error: compact failed: %s", err[0] ? err : "?");
    return;
  }
  after_session_change(t, "(session compacted)");
}

static void cmd_details(tui_t *t, char *arg, int *quit) {
  (void)arg;
  (void)quit;
  t->details_all = !t->details_all;
  push_system_line(t, "tool details: %s",
                   t->details_all ? "expanded" : "collapsed");
}

static void cmd_quit(tui_t *t, char *arg, int *quit) {
  (void)t;
  (void)arg;
  *quit = 1;
}

static const slash_cmd_t SLASH[] = {
    {"help", "?", "", "list commands and keys", 1, cmd_help},
    {"new", "clear", "", "start a new session", 0, cmd_new},
    {"session", "sessions resume", "[id]", "pick or switch session", 0,
     cmd_session},
    {"rename", "", "<title>", "name the current session", 1, cmd_rename},
    {"delete", "", "[id]", "delete a session (asks first)", 0, cmd_delete},
    {"model", "", "[name]", "pick or set the model", 0, cmd_model},
    {"provider", "", "[name]", "switch provider (asks for its key)", 0,
     cmd_provider},
    {"key", "apikey", "", "enter or replace the provider's API key", 0,
     cmd_key},
    {"effort", "think", "[low|medium|high|max]", "reasoning effort", 0,
     cmd_effort},
    {"protocol", "", "[name]", "pick or set the tool-call protocol", 0,
     cmd_protocol},
    {"tools", "", "[on|off NAME|minimal]", "list or toggle tools", 0,
     cmd_tools},
    {"permissions", "perms", "[reset]", "show saved always-allow rules", 1,
     cmd_permissions},
    {"yolo", "", "", "toggle auto-approve for this run", 1, cmd_yolo},
    {"max-steps", "", "[N]", "tool steps allowed per turn", 1, cmd_max_steps},
    {"status", "", "", "session, model, context and settings", 1, cmd_status},
    {"todo", "tasks", "", "show the agent's task list", 1, cmd_todo},
    {"undo", "", "", "revert file changes of the last turn", 0, cmd_undo},
    {"retry", "", "", "drop the last reply and ask again", 0, cmd_retry},
    {"diff", "", "[path]", "git status + diff of the workspace", 1, cmd_diff},
    {"compact", "summarize", "", "summarize the context to save tokens", 0,
     cmd_compact},
    {"export", "", "[file]", "write the transcript as Markdown", 1,
     cmd_export},
    {"copy", "", "", "copy the last reply (OSC 52)", 1, cmd_copy},
    {"init", "", "", "have the agent write AGENTS.md", 0, cmd_init},
    {"details", "", "", "expand/collapse all tool output", 1, cmd_details},
    {"quit", "q exit", "", "quit", 1, cmd_quit},
};

static const slash_cmd_t *slash_table(int *n) {
  *n = (int)(sizeof(SLASH) / sizeof(SLASH[0]));
  return SLASH;
}

static int has_alias(const char *list, const char *name) {
  size_t n = strlen(name);
  for (const char *p = list; *p;) {
    size_t w = strcspn(p, " ");
    if (w == n && strncmp(p, name, n) == 0)
      return 1;
    p += w;
    while (*p == ' ')
      p++;
  }
  return 0;
}

/* Exact name, alias, or unique prefix. */
static const slash_cmd_t *slash_find(const char *name, int *ambiguous) {
  int n;
  const slash_cmd_t *tab = slash_table(&n), *hit = NULL;
  *ambiguous = 0;
  for (int i = 0; i < n; i++)
    if (strcmp(tab[i].name, name) == 0 || has_alias(tab[i].aliases, name))
      return &tab[i];
  size_t len = strlen(name);
  for (int i = 0; len && i < n; i++) {
    if (strncmp(tab[i].name, name, len) == 0) {
      if (hit)
        *ambiguous = 1;
      hit = &tab[i];
    }
  }
  return *ambiguous ? NULL : hit;
}

static int handle_slash(tui_t *t, const char *line, int *should_quit) {
  *should_quit = 0;
  if (!line || line[0] != '/')
    return 0;
  char buf[INPUT_CAP];
  snprintf(buf, sizeof(buf), "%s", line + 1);
  char *cmd = buf;
  while (*cmd == ' ')
    cmd++;
  char *arg = cmd + strcspn(cmd, " \n");
  if (*arg) {
    *arg++ = 0;
    while (*arg == ' ')
      arg++;
  }
  size_t al = strlen(arg);
  while (al && (arg[al - 1] == ' ' || arg[al - 1] == '\n'))
    arg[--al] = 0;
  int amb = 0;
  const slash_cmd_t *c = slash_find(cmd, &amb);
  if (!c) {
    push_system_line(t, amb ? "Ambiguous command /%s (try /help)"
                            : "Unknown command /%s (try /help)",
                     cmd);
    return 1;
  }
  if (t->busy && !c->busy_ok) {
    push_system_line(t, "/%s is not available while the agent is working "
                        "(Esc cancels the turn)",
                     c->name);
    return 1;
  }
  c->fn(t, arg, should_quit);
  status_idle(t);
  return 1;
}

/* --- completion ----------------------------------------------------------- */

static void load_files(tui_t *t) {
  if (t->files && since_ms(&t->files_at) < 10000)
    return;
  for (int i = 0; i < t->nfiles; i++)
    free(t->files[i]);
  free(t->files);
  const cst_agent_config_t *cfg = cst_agent_config(t->agent);
  t->nfiles = cst_workspace_files(cfg->workspace_root, &t->files, 20000);
  clock_gettime(CLOCK_MONOTONIC, &t->files_at);
}

static void update_completion(tui_t *t) {
  t->comp_n = 0;
  if (t->comp_off || t->in_paste)
    return;
  if (t->inbuf[0] == '/' && memchr(t->inbuf, ' ', t->cur) == NULL &&
      memchr(t->inbuf, '\n', t->in_len) == NULL) {
    int n;
    const slash_cmd_t *tab = slash_table(&n);
    size_t len = t->cur - 1;
    for (int i = 0; i < n && t->comp_n < COMP_MAX; i++) {
      if (strncmp(tab[i].name, t->inbuf + 1, len) != 0)
        continue;
      comp_item_t *c = &t->comp[t->comp_n++];
      snprintf(c->text, sizeof(c->text), "/%s %s", tab[i].name, tab[i].args);
      snprintf(c->desc, sizeof(c->desc), "%s", tab[i].desc);
    }
    t->comp_kind = 1;
    t->comp_start = 0;
  } else {
    size_t st = t->cur;
    while (st > 0 && t->inbuf[st - 1] != ' ' && t->inbuf[st - 1] != '\n')
      st--;
    if (st >= t->in_len || t->inbuf[st] != '@')
      return;
    char frag[256];
    snprintf(frag, sizeof(frag), "%.*s", (int)(t->cur - st - 1),
             t->inbuf + st + 1);
    load_files(t);
    /* basename prefix matches first, then any substring */
    for (int pass = 0; pass < 2 && t->comp_n < COMP_MAX; pass++) {
      for (int i = 0; i < t->nfiles && t->comp_n < COMP_MAX; i++) {
        const char *f = t->files[i];
        const char *base = strrchr(f, '/');
        base = base ? base + 1 : f;
        int hit = pass == 0 ? strncasecmp(base, frag, strlen(frag)) == 0
                            : (strncasecmp(base, frag, strlen(frag)) != 0 &&
                               strcasestr(f, frag) != NULL);
        if (!hit)
          continue;
        comp_item_t *c = &t->comp[t->comp_n++];
        snprintf(c->text, sizeof(c->text), "@%s", f);
        c->desc[0] = 0;
      }
    }
    t->comp_kind = 2;
    t->comp_start = st;
  }
  if (t->comp_sel >= t->comp_n)
    t->comp_sel = t->comp_n ? t->comp_n - 1 : 0;
}

/* Returns the chosen slash command when the popup was a slash list. */
static const slash_cmd_t *accept_completion(tui_t *t) {
  if (t->comp_n <= 0)
    return NULL;
  const comp_item_t *c = &t->comp[t->comp_sel];
  const slash_cmd_t *cmd = NULL;
  char repl[300];
  if (t->comp_kind == 1) {
    char name[64];
    snprintf(name, sizeof(name), "%.*s", (int)strcspn(c->text + 1, " "),
             c->text + 1);
    int amb;
    cmd = slash_find(name, &amb);
    snprintf(repl, sizeof(repl), "/%s ", name);
  } else {
    snprintf(repl, sizeof(repl), "%s ", c->text);
  }
  size_t from = t->comp_start, to = t->cur;
  input_erase(t, from, to);
  t->cur = from;
  input_insert(t, repl, strlen(repl));
  t->comp_n = 0;
  t->comp_off = 1;
  return cmd;
}

static void toggle_think(tui_t *t) {
  int idx = t->focus_think_idx;
  if (idx < 0) {
    for (int i = t->hist.n - 1; i >= 0; i--) {
      if (t->hist.items[i].kind == BLK_THINK) {
        idx = i;
        break;
      }
    }
  }
  if (idx < 0 || idx >= t->hist.n)
    return;
  block_t *b = &t->hist.items[idx];
  if (b->kind != BLK_THINK)
    return;
  b->expanded = !b->expanded;
  /* Keep timed title (Thought · Ns) if already set. */
  if (b->expanded && (!b->title || !b->title[0]))
    block_set_title(b, "Thought");
  t->focus_think_idx = idx;
  draw_log(t);
}

static void toggle_last_tool(tui_t *t) {
  int idx = t->last_tool_idx;
  if (idx < 0 || idx >= t->hist.n) {
    for (int i = t->hist.n - 1; i >= 0; i--) {
      if (t->hist.items[i].kind == BLK_TOOL) {
        idx = i;
        break;
      }
    }
  }
  if (idx < 0 || idx >= t->hist.n)
    return;
  block_t *b = &t->hist.items[idx];
  if (b->kind != BLK_TOOL)
    return;
  b->expanded = !b->expanded;
  t->last_tool_idx = idx;
  draw_log(t);
}

/* --- turn worker ---------------------------------------------------------- */

typedef struct {
  tui_t *t;
  char *prompt;
} turn_arg_t;

static void *turn_thread(void *arg) {
  turn_arg_t *a = arg;
  tui_t *t = a->t;
  cst_agent_hooks_t hooks = {0};
  hooks.on_status = on_status;
  hooks.on_assistant_delta = on_assistant_delta;
  hooks.on_think_delta = on_think_delta;
  hooks.on_tool_event = on_tool_event;
  hooks.on_tool_result = on_tool_result;
  hooks.on_permission = on_permission;
  hooks.on_ask_user = on_ask_user;
  hooks.on_todo = on_todo;
  hooks.userdata = t;

  char err[512];
  err[0] = 0;
  int rc = cst_agent_run_turn_ex(t->agent, a->prompt, &hooks, err, sizeof(err));

  tui_lock(t);
  t->turn_rc = rc;
  snprintf(t->turn_err, sizeof(t->turn_err), "%s", err);
  collapse_open_think(t);
  if (t->as_live)
    live_seal(t);
  for (int i = 0; i < t->hist.n; i++) {
    if (t->hist.items[i].kind == BLK_TOOL)
      attach_tool_output_from_session(t, &t->hist.items[i]);
  }
  t->turn_done = 1;
  t->busy = 0;
  tui_mark_dirty(t);
  tui_unlock(t);

  free(a->prompt);
  free(a);
  return NULL;
}

static void request_cancel_ui(tui_t *t) {
  cst_agent_request_cancel(t->agent);
  set_status(t, "cancelling…");
  draw_status(t);
}

static int begin_turn(tui_t *t, char *prompt) {
  prompt_hist_push(t, prompt);
  block_t *ub = blocks_push(&t->hist);
  if (ub) {
    ub->kind = BLK_USER;
    block_set_title(ub, "You");
    block_set_body(ub, prompt, strlen(prompt));
    ub->expanded = 1;
  }
  t->think_idx = -1;
  t->log_scroll = 0;
  set_status(t, "streaming…");

  turn_arg_t *ta = calloc(1, sizeof(*ta));
  if (!ta) {
    free(prompt);
    return -1;
  }
  ta->t = t;
  ta->prompt = prompt;
  t->busy = 1;
  t->turn_done = 0;
  clock_gettime(CLOCK_MONOTONIC, &t->turn_t0);
  redraw_all(t);
  pthread_t th;
  if (pthread_create(&th, NULL, turn_thread, ta) != 0) {
    t->busy = 0;
    free(prompt);
    free(ta);
    push_system_line(t, "Error: failed to start turn thread");
    status_idle(t);
    redraw_all(t);
    return -1;
  }
  pthread_detach(th);
  return 0;
}

/* Owns prompt. Returns 0 ok, -1 fail, -2 quit. */
static int start_turn(tui_t *t, char *prompt) {
  if (!prompt)
    return -1;
  if (prompt[0] == '/') {
    int should_quit = 0;
    handle_slash(t, prompt, &should_quit);
    free(prompt);
    t->log_scroll = 0;
    if (t->need_layout) {
      t->need_layout = 0;
      layout(t);
      wtimeout(t->input, 80);
    }
    redraw_all(t);
    if (should_quit)
      return -2;
    if (t->pending_prompt && !t->busy) {
      char *next = t->pending_prompt;
      t->pending_prompt = NULL;
      return begin_turn(t, next);
    }
    return 0;
  }
  return begin_turn(t, prompt);
}

static int try_start_queued(tui_t *t) {
  if (t->busy || t->queue_n <= 0)
    return 0;
  char *next = queue_pop(t);
  if (!next)
    return 0;
  return start_turn(t, next);
}

static int submit_input(tui_t *t, int busy) {
  if (t->in_len == 0) {
    if (!busy && t->queue_n > 0)
      return try_start_queued(t);
    if (!busy)
      toggle_last_tool(t);
    return 0;
  }

  cst_agent_config_t *cfg = cst_agent_config_mut(t->agent);
  if (!busy && t->inbuf[0] != '/' && !cfg->api_key[0]) {
    char key[512];
    if (obtain_key(t, cfg->provider, key, sizeof(key), 0) != 0) {
      push_system_line(t, "No API key for %s yet — /key to enter one, or "
                          "/provider to switch",
                       cfg->provider);
      return 0;
    }
    snprintf(cfg->api_key, sizeof(cfg->api_key), "%s", key);
    memset(key, 0, sizeof(key));
  }

  char *prompt = strdup(t->inbuf);
  input_clear(t);
  layout_maybe_grow_input(t);
  if (!prompt)
    return 0;

  if (busy && prompt[0] == '/') {
    int q = 0;
    handle_slash(t, prompt, &q);
    free(prompt);
    redraw_all(t);
    return q ? -2 : 0;
  }
  if (busy) {
    if (queue_push(t, prompt) != 0) {
      push_system_line(t, "(queue full — max %d)", QUEUE_CAP);
      set_status(t, "queue full");
    } else {
      char msg[64];
      snprintf(msg, sizeof(msg), "queued (%d)", t->queue_n);
      set_status(t, msg);
    }
    free(prompt);
    draw_status(t);
    return 0;
  }
  return start_turn(t, prompt);
}

/* --- modal key loops ------------------------------------------------------ */

static void perm_answer(tui_t *t, int ans) {
  tui_lock(t);
  t->perm_ans = ans;
  tui_unlock(t);
}

static void run_perm_modal(tui_t *t) {
  wtimeout(t->input, -1);
  curs_set(0);
  for (;;) {
    draw_perm_modal(t);
    draw_status(t);
    wint_t wch = 0;
    int rc = wget_wch(t->input, &wch);
    if (rc == ERR)
      continue;
    if (rc == KEY_CODE_YES) {
      int h = getmaxy(t->logw);
      if (wch == KEY_RESIZE)
        layout(t), wtimeout(t->input, -1), redraw_all(t);
      else if (wch == KEY_UP)
        t->perm_scroll--;
      else if (wch == KEY_DOWN)
        t->perm_scroll++;
      else if (wch == KEY_PPAGE)
        t->perm_scroll -= h / 2;
      else if (wch == KEY_NPAGE)
        t->perm_scroll += h / 2;
      else if (wch == KEY_ENTER) {
        perm_answer(t, CST_PERM_ONCE);
        break;
      }
      continue;
    }
    if (wch == L'y' || wch == L'Y' || wch == 10 || wch == 13) {
      perm_answer(t, CST_PERM_ONCE);
      break;
    }
    if (wch == L'n' || wch == L'N' || wch == 27) {
      perm_answer(t, CST_PERM_DENY);
      break;
    }
    if (wch == 3) { /* Ctrl+C: deny and stop the turn */
      perm_answer(t, CST_PERM_DENY);
      request_cancel_ui(t);
      break;
    }
    if (wch == L'a' || wch == L'A') {
      perm_answer(t, CST_PERM_ALWAYS_TOOL);
      break;
    }
    if ((wch == L'p' || wch == L'P') && t->perm_prefix[0]) {
      perm_answer(t, CST_PERM_ALWAYS_PREFIX);
      break;
    }
  }
  curs_set(1);
  wtimeout(t->input, 80);
  redraw_all(t);
}

static void ask_finish(tui_t *t, int rc) {
  tui_lock(t);
  if (rc == 0 && !t->ask_buf[0] && t->ask_nopts)
    snprintf(t->ask_buf, sizeof(t->ask_buf), "%s", t->ask_opts[t->ask_sel]);
  t->ask_rc = rc;
  t->ask_done = 1;
  tui_unlock(t);
}

static void run_ask_modal(tui_t *t) {
  wtimeout(t->input, -1);
  curs_set(0);
  for (;;) {
    draw_ask_modal(t);
    wint_t wch = 0;
    int rc = wget_wch(t->input, &wch);
    if (rc == ERR)
      continue;
    if (rc == KEY_CODE_YES) {
      if (wch == KEY_RESIZE)
        layout(t), wtimeout(t->input, -1), redraw_all(t);
      else if (wch == KEY_UP && t->ask_sel > 0)
        t->ask_sel--;
      else if (wch == KEY_DOWN && t->ask_sel + 1 < t->ask_nopts)
        t->ask_sel++;
      else if (wch == KEY_BACKSPACE) {
        size_t n = strlen(t->ask_buf);
        t->ask_buf[n - utf8_prev_len(t->ask_buf, n)] = 0;
      } else if (wch == KEY_ENTER && (t->ask_buf[0] || t->ask_nopts)) {
        ask_finish(t, 0);
        break;
      }
      continue;
    }
    if (wch == 27 || wch == 3) {
      ask_finish(t, -1);
      break;
    }
    if (wch == 10 || wch == 13) {
      if (t->ask_buf[0] || t->ask_nopts) {
        ask_finish(t, 0);
        break;
      }
      continue;
    }
    if (wch == 127 || wch == 8) {
      size_t n = strlen(t->ask_buf);
      t->ask_buf[n - utf8_prev_len(t->ask_buf, n)] = 0;
      continue;
    }
    if (!t->ask_buf[0] && wch >= L'1' && wch <= L'9' &&
        (int)(wch - L'1') < t->ask_nopts) {
      t->ask_sel = (int)(wch - L'1');
      ask_finish(t, 0);
      break;
    }
    if (iswprint(wch)) {
      char mb[8];
      mbstate_t st;
      memset(&st, 0, sizeof(st));
      size_t k = wcrtomb(mb, (wchar_t)wch, &st);
      size_t n = strlen(t->ask_buf);
      if (k != (size_t)-1 && n + k + 1 < sizeof(t->ask_buf)) {
        memcpy(t->ask_buf + n, mb, k);
        t->ask_buf[n + k] = 0;
      }
    }
  }
  curs_set(1);
  wtimeout(t->input, 80);
  redraw_all(t);
}

/* --- main loop ------------------------------------------------------------ */

static void tui_free(tui_t *t) {
  queue_free_all(t);
  for (int i = 0; i < t->prompt_hist_n; i++)
    free(t->prompt_hist[i]);
  for (int i = 0; i < t->nfiles; i++)
    free(t->files[i]);
  free(t->files);
  free(t->todo);
  free(t->pending_prompt);
  free(t->perm_preview);
  live_end_cleanup(t);
  if (t->header)
    delwin(t->header);
  if (t->logw)
    delwin(t->logw);
  if (t->todow)
    delwin(t->todow);
  if (t->status)
    delwin(t->status);
  if (t->input)
    delwin(t->input);
  blocks_free(&t->hist);
  pthread_mutex_destroy(&t->mu);
}

/* Redraw after an edit; the transcript only when the popup changed. */
static void after_edit(tui_t *t) {
  layout_maybe_grow_input(t);
  if (t->comp_n || t->comp_drawn) {
    draw_log(t);
    draw_input(t);
  }
}

static void insert_newline(tui_t *t) {
  input_put_byte(t, '\n');
  layout_maybe_grow_input(t);
}

/* Paste mode: keep newlines/tabs literally; redraw once at the end. */
static void paste_char(tui_t *t, wint_t wch) {
  if (wch == 13) {
    input_put_byte(t, '\n');
    t->paste_cr = 1;
    return;
  }
  if (wch == 10) {
    if (!t->paste_cr)
      input_put_byte(t, '\n');
    t->paste_cr = 0;
    return;
  }
  t->paste_cr = 0;
  if (wch == L'\t')
    input_insert(t, "    ", 4);
  else if (iswprint(wch) || wcwidth((wchar_t)wch) > 0)
    input_put_wc(t, (wchar_t)wch);
}

int cst_tui_run(cst_agent_t *agent) {
  if (!setlocale(LC_ALL, ""))
    setlocale(LC_ALL, "C.UTF-8");
#ifndef _WIN32
  if (!getenv("ESCDELAY"))
    setenv("ESCDELAY", "25", 0);
#endif

  initscr();
  raw(); /* Ctrl+C/Ctrl+Z reach us as keys instead of signals */
  noecho();
  keypad(stdscr, TRUE);
  curs_set(1);
  theme_init();
#ifdef NCURSES_VERSION
  define_key("\033[200~", KEY_PASTE_BEGIN);
  define_key("\033[201~", KEY_PASTE_END);
  printf("\033[?2004h");
  fflush(stdout);
#endif

  tui_t t;
  memset(&t, 0, sizeof(t));
  t.agent = agent;
  t.think_idx = -1;
  t.last_tool_idx = -1;
  t.focus_think_idx = -1;
  t.hist_browse = -1;
  t.show_todo = 1;
  pthread_mutex_init(&t.mu, NULL);
  blocks_init(&t.hist);
  if (!t.hist.items) {
    endwin();
    return -1;
  }

  refresh_title(&t);
  refresh_todo(&t);
  layout(&t);
  t.need_layout = 0;
  reload_hist_from_session(&t);
  status_idle(&t);
  redraw_all(&t);
  wtimeout(t.input, 80);

  cst_agent_config_t *cfg = cst_agent_config_mut(agent);
  cst_settings_t first;
  if (!cfg->api_key[0] && cst_settings_load(&first) != 0) {
    int ignore = 0;
    cmd_provider(&t, NULL, &ignore);
  }
  if (!cfg->api_key[0]) {
    char key[512];
    if (obtain_key(&t, cfg->provider, key, sizeof(key), 0) == 0)
      snprintf(cfg->api_key, sizeof(cfg->api_key), "%s", key);
    else
      push_system_line(&t, "No API key for %s yet — /key to enter one, or "
                           "/provider to switch",
                       cfg->provider);
    memset(key, 0, sizeof(key));
  }
  cst_settings_remember(cfg);
  redraw_all(&t);

  for (;;) {
    tui_lock(&t);
    int dirty = t.dirty;
    int turn_done = t.turn_done;
    int turn_rc = t.turn_rc;
    char turn_err[512];
    snprintf(turn_err, sizeof(turn_err), "%s", t.turn_err);
    int perm_ask = t.perm_ask && t.perm_ans < 0;
    int ask = t.ask_pending && !t.ask_done;
    int busy = t.busy;
    int relayout = t.need_layout;
    t.need_layout = 0;
    t.dirty = 0;
    if (turn_done)
      t.turn_done = 0;
    tui_unlock(&t);

    if (relayout) {
      layout(&t);
      wtimeout(t.input, 80);
      dirty = 1;
    }
    if (dirty)
      redraw_all(&t);
    if (busy) {
      t.spin++;
      draw_header(&t);
      draw_input(&t);
    }

    if (turn_done) {
      if (turn_rc != 0) {
        push_system_line(&t, "Error: %s", turn_err[0] ? turn_err : "?");
        set_status(&t, turn_err[0] ? turn_err : "turn failed");
      } else {
        status_idle(&t);
      }
      cst_agent_reload_notes(t.agent);
      refresh_title(&t);
      t.log_scroll = 0;
      redraw_all(&t);
      if (try_start_queued(&t) == -2)
        break;
      continue;
    }

    if (perm_ask) {
      run_perm_modal(&t);
      continue;
    }
    if (ask) {
      run_ask_modal(&t);
      continue;
    }

    wint_t wch = 0;
    int rc = wget_wch(t.input, &wch);
    if (rc == ERR)
      continue;

    if (rc == KEY_CODE_YES) {
      if (wch == KEY_PASTE_BEGIN) {
        t.in_paste = 1;
        t.paste_cr = 0;
        continue;
      }
      if (wch == KEY_PASTE_END) {
        t.in_paste = 0;
        input_changed(&t);
        after_edit(&t);
        continue;
      }
      if (wch == KEY_RESIZE) {
        layout(&t);
        wtimeout(t.input, 80);
        redraw_all(&t);
        continue;
      }
      if (wch == KEY_MOUSE) {
        MEVENT ev;
        if (getmouse(&ev) == OK) {
          if (ev.bstate & BUTTON4_PRESSED) {
            t.log_scroll += SCROLL_SPEED;
            draw_log(&t);
          } else if (ev.bstate & BUTTON5_PRESSED) {
            t.log_scroll -= SCROLL_SPEED;
            if (t.log_scroll < 0)
              t.log_scroll = 0;
            draw_log(&t);
          }
        }
        continue;
      }
      switch (wch) {
      case KEY_PPAGE:
        t.log_scroll += t.rows / 2;
        draw_log(&t);
        continue;
      case KEY_NPAGE:
        t.log_scroll -= t.rows / 2;
        if (t.log_scroll < 0)
          t.log_scroll = 0;
        draw_log(&t);
        continue;
      case KEY_HOME:
        if (t.in_len) {
          t.cur = line_start(&t, t.cur);
          draw_input(&t);
        } else {
          t.log_scroll = 1 << 28; /* clamped by draw_log */
          draw_log(&t);
        }
        continue;
      case KEY_END:
        if (t.in_len) {
          t.cur = line_end(&t, t.cur);
          draw_input(&t);
        } else {
          t.log_scroll = 0;
          draw_log(&t);
        }
        continue;
      case KEY_LEFT:
        t.cur -= utf8_prev_len(t.inbuf, t.cur);
        update_completion(&t);
        redraw_all(&t);
        continue;
      case KEY_RIGHT:
        t.cur += next_len(&t, t.cur);
        update_completion(&t);
        redraw_all(&t);
        continue;
      case KEY_UP:
      case KEY_DOWN: {
        int dir = wch == KEY_UP ? -1 : 1;
        if (t.comp_n > 0) {
          t.comp_sel = (t.comp_sel + dir + t.comp_n) % t.comp_n;
          draw_log(&t);
          draw_input(&t);
          continue;
        }
        if (input_line_move(&t, dir)) {
          draw_input(&t);
          continue;
        }
        if (dir < 0) {
          if (t.prompt_hist_n <= 0)
            continue;
          int idx = t.hist_browse;
          idx = idx < 0 ? t.prompt_hist_n - 1 : (idx > 0 ? idx - 1 : 0);
          hist_load_into_input(&t, idx);
        } else {
          if (t.hist_browse < 0)
            continue;
          if (t.hist_browse + 1 >= t.prompt_hist_n)
            input_clear(&t);
          else
            hist_load_into_input(&t, t.hist_browse + 1);
        }
        after_edit(&t);
        continue;
      }
      case KEY_BACKSPACE:
        input_erase(&t, t.cur - utf8_prev_len(t.inbuf, t.cur), t.cur);
        after_edit(&t);
        continue;
      case KEY_DC:
        input_erase(&t, t.cur, t.cur + next_len(&t, t.cur));
        after_edit(&t);
        continue;
      case KEY_BTAB:
        if (t.comp_n > 0) {
          t.comp_sel = (t.comp_sel + t.comp_n - 1) % t.comp_n;
          draw_log(&t);
        }
        continue;
      case KEY_ENTER:
        break; /* handled with CR below */
      default:
        continue;
      }
      wch = 13;
    }

    if (t.in_paste) {
      paste_char(&t, wch);
      continue;
    }

    /* Enter: accept a completion, otherwise send. */
    if (wch == 10 || wch == 13) {
      if (t.comp_n > 0) {
        int kind = t.comp_kind;
        const slash_cmd_t *c = accept_completion(&t);
        after_edit(&t);
        /* "/he⏎" runs /help; commands that need an argument wait for it */
        if (kind != 1 || !c || c->args[0] == '<')
          continue;
      }
      int st = submit_input(&t, busy);
      if (st == -2)
        break;
      continue;
    }

    if (wch == 3) { /* Ctrl+C */
      if (busy) {
        request_cancel_ui(&t);
      } else if (t.in_len) {
        input_clear(&t);
        after_edit(&t);
      } else if (t.ctrlc_at.tv_sec && since_ms(&t.ctrlc_at) < 2000) {
        break;
      } else {
        clock_gettime(CLOCK_MONOTONIC, &t.ctrlc_at);
        set_status(&t, "press Ctrl+C again to quit");
        draw_status(&t);
      }
      continue;
    }
    if (wch == 4) { /* Ctrl+D on an empty prompt quits */
      if (!busy && t.in_len == 0)
        break;
      input_erase(&t, t.cur, t.cur + next_len(&t, t.cur));
      layout_maybe_grow_input(&t);
      continue;
    }

    if (wch == 27) {
      /* Alt+key arrives as Esc followed by the key */
      wint_t nx = 0;
      wtimeout(t.input, 30);
      int r2 = wget_wch(t.input, &nx);
      wtimeout(t.input, 80);
      if (r2 == OK) {
        if (nx == 13 || nx == 10)
          insert_newline(&t);
        else if (nx == L'b')
          t.cur = word_left(&t, t.cur), draw_input(&t);
        else if (nx == L'f')
          t.cur = word_right(&t, t.cur), draw_input(&t);
        else if (nx == 127 || nx == 8) {
          input_erase(&t, word_left(&t, t.cur), t.cur);
          layout_maybe_grow_input(&t);
        }
        continue;
      }
      if (t.comp_n > 0) {
        t.comp_off = 1;
        t.comp_n = 0;
        draw_log(&t);
      } else if (busy) {
        request_cancel_ui(&t);
      } else if (t.in_len) {
        input_clear(&t);
        layout_maybe_grow_input(&t);
      }
      continue;
    }

    switch (wch) {
    case 1: /* Ctrl+A */
      t.cur = line_start(&t, t.cur);
      draw_input(&t);
      continue;
    case 5: /* Ctrl+E */
      t.cur = line_end(&t, t.cur);
      draw_input(&t);
      continue;
    case 2: /* Ctrl+B */
      t.cur -= utf8_prev_len(t.inbuf, t.cur);
      draw_input(&t);
      continue;
    case 6: /* Ctrl+F */
      t.cur += next_len(&t, t.cur);
      draw_input(&t);
      continue;
    case 11: /* Ctrl+K */
      input_erase(&t, t.cur, line_end(&t, t.cur) == t.cur && t.cur < t.in_len
                                 ? t.cur + 1
                                 : line_end(&t, t.cur));
      after_edit(&t);
      continue;
    case 21: /* Ctrl+U */
      input_erase(&t, line_start(&t, t.cur), t.cur);
      after_edit(&t);
      continue;
    case 23: /* Ctrl+W */
      input_erase(&t, word_left(&t, t.cur), t.cur);
      after_edit(&t);
      continue;
    case 14: /* Ctrl+N */
      insert_newline(&t);
      continue;
    case 15: /* Ctrl+O */
      toggle_last_tool(&t);
      continue;
    case 20: /* Ctrl+T */
      t.show_todo = !t.show_todo;
      layout(&t);
      wtimeout(t.input, 80);
      redraw_all(&t);
      continue;
    case 12: /* Ctrl+L */
      clearok(curscr, TRUE);
      redraw_all(&t);
      continue;
    case 26: /* Ctrl+Z is not job control in raw mode */
      continue;
    case L'\t':
      if (t.comp_n > 0) {
        accept_completion(&t);
        after_edit(&t);
      } else if (t.in_len == 0) {
        toggle_think(&t);
      } else {
        t.comp_off = 0;
        update_completion(&t);
        draw_log(&t);
        draw_input(&t);
      }
      continue;
    case 127:
    case 8:
      input_erase(&t, t.cur - utf8_prev_len(t.inbuf, t.cur), t.cur);
      after_edit(&t);
      continue;
    default:
      break;
    }

    if (iswprint(wch) || wcwidth((wchar_t)wch) > 0) {
      input_put_wc(&t, (wchar_t)wch);
      after_edit(&t);
    }
  }

  if (t.busy) {
    cst_agent_request_cancel(t.agent);
    for (int i = 0; i < 50 && t.busy; i++)
      usleep(100000);
  }

  tui_free(&t);
#ifdef NCURSES_VERSION
  printf("\033[?2004l");
  fflush(stdout);
#endif
  endwin();
  return 0;
}