The settings dialog could pick a preset, a model and a key and nothing else.
Two things were missing: a provider the presets do not know, and what the
model is asked to do while it answers. Both live under "Advanced options"
now, next to the entry they belong to.
Custom providers (engine)
- cst_models_user_set_provider() / cst_models_user_drop_provider() write the
engine's own user layer, <config>/cst-agent/models.json:
{"providers": {"myllm": {"api_base": ..., "key_env": ...,
"default_model": ..., "models": [...]}}}
and reload the registry, so the provider is at once in the provider list,
in the wire models[] and in the CLI's /provider -- the file a hand-written
override would go into is the same one, so the GUI and an editor agree.
The name is checked (1-31 of letters, digits, '.', '_', '-'), a preset's
name overrides that preset (a self-hosted endpoint, a proxy), everything
else in the file (model rules) is kept, and a file that is not a JSON
object is never overwritten. Dropping only removes the user's own entry.
- AgentCore::providers() gained "custom" (source == "user"), and
addProvider() / removeProvider() drive the two calls above.
Model parameters (engine + wire)
- cst_agent_config_t and cst_llm_request_t carry temperature, top_p and
max_tokens. 0 means the field is not sent at all -- an absent field is the
provider's own default, which "temperature": 0 is not (deterministic
decoding is a real choice), so cst_llm_build_body() only adds what was set.
tests/test_llm_body.c:test_gen_params pins both halves.
- settings.json keeps them per provider ("params": {...}) via
cst_settings_remember_params(); cst_settings_remember() carries them along
with the provider choice, and cst_agent_create() reads them, so a CLI or
TUI run sends what the window was set to. An all-zero config (the CLI)
leaves what the GUI saved alone.
- AgentCore::genParams() / setGenParams(), and useProvider() applies both the
remembered parameters of the provider it lands on and a base URL that was
edited in the dialog.
The dialog
- Rewritten around one scrolling body with a fixed footer: a long model list
used to push the key field and the buttons out of the dialog. The model
chips are filtered (a filter field appears past twelve) and capped at 40
with "... +N more", which is what a router with hundreds of models needs.
- "Advanced options" folds out the provider entry (name, base URL, key
variable, default model, models; Save provider / Remove from models.json)
and the model parameters (temperature, top-p, max tokens; empty = not
sent). The fields follow the picked provider and are what gets saved, so a
hand-typed edit is never lost to a stale property.
Verified: --uitest 67/67 (15 new checks: parameters round-trip through the
engine, a provider added through the form and removed again, a bad name
refused, a preset not removable), --selftest, ctest cst-app-selftest, and
make check with the new body test.
Version 0.8.15.
mode = coding
Working mode: --mode coding|general (CST_MODE, settings.json, /mode,
WebUI run settings). general swaps the default framing for a general
assistant one -- workflow, safety notes, tool wording (run_shell, the
subagents) -- and /status shows it; minimal (the paper profile) stays
byte-frozen. The prompt state carries the mode so a switch leaves a
system note in history.
Clipboard: clipboard_read / clipboard_write tools (16 MiB cap read,
default 64 KiB window; writing is a WRITE permission with a preview) on
pbcopy / wl-copy / xclip / pbpaste / wl-paste / xclip and the Win32
clipboard. In the TUI, /attach paste falls back to clipboard text when
there is no image on it.
PDF: a dependency-free text extractor (src/pdf_text.c): inflate,
Flate/ASCIIHex/ASCII85, PNG/TIFF predictors, layout-independent object
scan, object streams, page tree walk with inherited resources, content
lexer (Tj/TJ/'/" and the Td/TD/T*/Tm spacing heuristics), per-font
ToUnicode CMaps and inline images skipped. Encrypted files and pages
with no text layer are refused with the reason.
Attachments: /attach (a path or files dropped on the terminal) now take
images, PDFs and text. A PDF is stored as its text layer with the mime
still saying application/pdf and its page count; anything else has to be
UTF-8 text. Documents travel inline as text parts, so CST_NO_IMAGES and
text-only models no longer drop them, while images keep their old path.
Tests: test_pdf_text (plain, bare and zlib-framed Flate, inline image,
CID + ToUnicode, object stream, error paths), documents in test_attach,
inlined documents in test_llm_body, mode in test_config.
Sessions: rename, delete and search; /api/retry regenerates the last
answer, editing a prompt resends from there; /api/export downloads the
transcript as Markdown (cst_session_export_md). Session messages carry
note/tool_result markers, so a reload rebuilds the tool steps with
their arguments, output and exit status; subagent progress is shown.
Diff and settings: /api/diff shows the real diff; /api/settings covers
protocol, max_steps, tool switches and confirm; /api/permissions edits
the rules; sandbox status is reported. Session rename no longer reads
past a short title.
Commands: slash commands with completion in the composer (/model,
/provider, /new, /retry, /undo, /compact, /export, /diff, /init,
/skill and more), a Ctrl+P palette, Shift+Tab cycles the approval
mode, F1 or ? shows the keys. "Thinking expanded" is saved in the
settings (show_thinking), "expand all tool output" in the browser.
Extensions: GET /api/extensions lists MCP servers, plugins, skills,
agent roles and subagent runs; POST /api/extensions/reload and
/api/extensions/trust; a workspace switch reloads them. /api/init and
/api/skill run on the server (cst_init_prompt shared with the TUI).
Errors, statuses and [cst] notes are shown in Chinese with a readable
reason instead of rc=; a failed turn's error survives the reload.
Tests: scripts/e2e_webui_sessions.py, e2e_webui_workspace.py and
e2e_webui_ext.py, run from e2e_webui.sh.
The front end is rebuilt on the design tokens the desktop app ships (surfaces,
color-mix borders, alpha hovers, accent): a 30-icon inline SVG sprite, dark and
light themes, layout switches as deep links (?side=0, ?panel=0, ?theme=light)
resolved before the first paint. The empty page is one line and leaves with the
first turn; the right rail keeps three cards - todo, file changes (+N -M) and
context (tokens, prompt cache hit rate). Both rails animate in and out, and a
collapsed rail widens its grid track to 0 instead of being removed, so the
transcript never slides into a zero-width column.
- src/webui.c: POST /api/workspace - re-root the agent at another directory
(permission rules, metrics, AGENTS.md follow) and start a session there, as
sessions live per directory; state also reports cached/cache_miss tokens
- src/agent_loop.c: cst_agent_set_workspace(), rebuilt prompt and re-measured
budget; the auto-compact threshold is 75% of the window (was 60%)
- src/tui.c: /web forks a WebUI next to the TUI - separate process and a new
session, because cst_webui_run() blocks and two writers corrupt one session
- src/os_compat.c, src/os_win.c: run_shell runs without a time limit unless
CST_SHELL_TIMEOUT asks for one, so builds and long clones finish
- src/main.c, include/cst_webui.h: one CST_WEBUI_DEFAULT_PORT for --help, the
docs and /web; Termux opens the browser through termux-open-url
- README.md, docs/webui.md, docs/env_openai.md: /web, /api/workspace, the new
state fields, the 75% threshold and the layout deep links
tests/e2e_webui.sh green (permission round-trip, token paths, --web-dev);
make check green.
Images
- vision gate: text-only models get a note instead of image parts and no
view_image tool; unknown models retry once without images on HTTP 400
- paste: Ctrl+V and /attach paste read the clipboard (wl-paste, xclip,
pngpaste/osascript, Win32 PNG or CF_DIB converted to PNG); pasting image
file paths attaches them
- MCP image content is stored in the session and sent with the tool result
- attach: rel path validation, base64 decode, /retry keeps images
Model registry
- built-in src/models_builtin.json embedded at build time, merged with
<config>/models.json and cached GET /models metadata (context, vision,
pricing); most specific rule wins per field
- /model labels, /status source, --list-models [provider]
Cache and cost
- stable request prefix (frozen tools, notes as messages), DeepSeek prefix
completion, OpenAI/Anthropic cache hints, /cost and hit rate in the status
Tools
- Table-driven tool registry with permission classes and default/minimal
profiles; new tools: edit_file, list_dir, glob, grep, delete_file,
move_file, todo_write, web_fetch, ask_user (plus read_file paging).
- Built-in Myers diff; write tools return unified diffs.
- Persistent permission rules (.agent/permissions.json), per-turn undo
snapshots (.agent/undo), AGENTS.md project notes, auto-compact at 80%
of the model context, cancellable run_shell with process-group kill.
TUI
- Table-driven slash commands: /provider /key /effort /status /tools
/permissions /yolo /undo /retry /diff /export /copy /rename /delete
/init /max-steps /todo, with / and @ completion.
- Permission modal with diff and prefix rules, ask_user modal, todo
panel, header with model/effort/context, bracketed paste, line editing,
wide-char cursor, NO_COLOR and ASCII fallback; Esc never quits.
Startup and configuration
- API keys are entered in the TUI (hidden) and saved per provider in
<config>/credentials (0600); env variables are only a fallback.
- Last provider, per-provider model and reasoning effort are remembered
in <config>/settings.json; --effort/-e and /effort send
reasoning_effort (low|medium|high|max) to models that accept it.
- DeepSeek preset uses deepseek-flash / deepseek-v4-pro.
- Session flags --new/--continue/--resume/--list-sessions, --yolo,
--confirm.
Compatibility and tests
- ncurses detection, macOS/Homebrew support, make install, XDG config
dir, POSIX cleanups; Gitea CI (gcc/clang/asan/musl/macOS).
- Unit tests for diff, fs tools, registry, undo/perms and config;
e2e fixtures multi_file_refactor and ask_or_todo; vendored cJSON.
WHC