parity-matrix.md

title	Weasel Parity Matrix
description	Surface-by-surface mapping between chimera weasel and the upstream minimal harness — GREEN (at parity / superset), YELLOW (partial), RED (deferred or out of scope).

chimera weasel Parity Matrix

Source baseline: research/weasel/SPEC.md (Apr 2026), upstream minimal-harness source tree walk under packages/coding-agent/. Updated: wave-5 ship (W1–W6), refreshed 2026-04-30 by the wave-6 cross-CLI verification (X1–X3, I-series). Refreshed again at wave-9 close (W1/W2, O5) — three rows promoted (TS / JS extension execution; theme registry; prompt-template registry). Legend: GREEN = shipped / at parity (or superset); YELLOW = partial; RED = deferred or out of scope.

Wave-9 close (2026-04-30, D1). Two carry-over items from the wave-5 follow-up list landed in this wave:

• TS / JS extension execution. W1/W9 added a Node-subprocess bridge so a package.json-driven JS or TS extension can contribute callable tools to the weasel agent. New module chimera/weasel/node_executor.py (~340 LOC). 27 new tests in tests/weasel/test_node_executor.py. Fail-open when Node is missing.
• Theme + prompt-template registries. W2/W9 added two new core extension surfaces: chimera/weasel/themes.py (color palettes + REPL prompt-prefix bundles) and chimera/weasel/prompt_templates.py (markdown-with-frontmatter system prompts). Built-ins-then-user-then-project precedence, matching the existing extension loader. 38 new tests.

Plus the cross-CLI chimera completion generator (O5) covers weasel too. Reports live under research/weasel/{W1,W2}-W9-REPORT.md and research/O5-COMPLETION.md. Live pytest tests/weasel/ runs 267+ passed with the wave-9 additions; trademark scrub still exits OK at the codename-aggregate level (passed: 7).

Wave-6 verification (2026-04-30). Live state at handoff: uv run ruff check chimera/weasel/ clean; uv run mypy chimera/weasel/ clean (part of the 36-source-file mypy run that covers ferret + weasel + shrew); uv run pytest tests/weasel/ -q = 164 passed in ~0.5s. bash scripts/weasel_trademark_scrub.sh exits 0 on the full live source / docs / test scope. chimera weasel 0.5.0 boots, --help is brand-clean, and the four-mode dispatcher routes interactive / print / rpc / sdk end-to-end. Weasel is now Tier 1 alongside mink and otter.

Trademark hygiene. Throughout this document the upstream project is referred to as "the minimal harness" or "the upstream". Live references to filesystem paths such as .pi/ are kept because they are facts about directories weasel can opportunistically read on disk for users migrating, not brand claims. See security-and-trademarks.md.

Top-level surfaces

The upstream ships a single pi binary with four modes. Weasel mirrors the four-mode philosophy and reuses Chimera's infrastructure (eventlog, permissions, providers) for everything else.

Upstream surface	Weasel status	File	Notes
Interactive REPL	GREEN	chimera/weasel/repl.py	Streaming, mid-turn steering, Ctrl-C cancel, slash commands.
Print mode (-p)	GREEN	chimera/weasel/modes.py	Plain text, --json, NDJSON --stream-json.
Print mode JSON	GREEN	chimera/weasel/modes.py	chimera weasel -p "..." --json.
RPC mode (stdio)	GREEN	chimera/weasel/rpc.py	JSON-RPC 2.0, methods: prompt, steer, cancel, get_state, compact.
SDK	GREEN	chimera/weasel/sdk.py	from chimera.weasel.sdk import Agent; sync + async.
--list-models	GREEN	chimera/weasel/cli.py	Provider-driven catalogue.
Sessions list / show	GREEN	chimera/weasel/sessions.py	Reads ~/.chimera/eventlog/weasel-*/.
Session resume	GREEN	chimera/weasel/sessions.py	--resume <id>; SDK agent.resume(id).
Extension auto-discovery	GREEN	chimera/weasel/extensions.py	.weasel/extensions/*.{py,js,ts} + ~/.weasel/extensions/.
Settings file	GREEN	chimera/weasel/cli.py	.weasel/settings.json (model, allowed extensions).

CLI flag map

The upstream pi binary exposes a tight flag set (one-shot, streaming, model selection). Weasel mirrors the flags that affect agent semantics and adds the JSON / NDJSON outputs from the broader Chimera CLI vocabulary.

Upstream flag	Weasel status	Weasel equivalent	Notes
-p / --print	GREEN	-p / --print	Identical.
--json	GREEN	--json	Single JSON blob on stdout.
--stream-json	GREEN	--stream-json	NDJSON event stream.
--mode <m>	GREEN	--mode interactive|print|rpc	sdk is import-only.
--model / -m	GREEN	--model / -m	Same syntax.
--models (cycle list)	GREEN	--models a,b,c	REPL /model cycles.
--list-models	GREEN	--list-models	Provider-driven.
--cwd / --dir	GREEN	--cwd	Same.
--max-steps	GREEN	--max-steps	Same.
--allowed-tools	GREEN	--allowed-tools Read,Bash,...	Comma-separated allowlist.
--no-save	GREEN	--no-save	Skip eventlog.
--resume <id>	GREEN	--resume <id>	Rehydrate from eventlog.
--extensions-dir	GREEN	--extensions-dir	Override discovery root.
--no-extensions	GREEN	--no-extensions	Skip auto-discovery.
--allow-extensions <names>	GREEN	--allow-extensions a,b	Pre-approve in non-interactive.
--thinking	YELLOW	--thinking off|min|low|med|high|max	Surface from chimera.providers.thinking.
--verbose	GREEN	--verbose	Stream events to stderr.
--no-color	GREEN	--no-color	Plain output handler.
--api-key	YELLOW	env var preferred	Inline flag deferred for security; env vars are the path.
--base-url	GREEN	--base-url	OpenAI-compatible endpoints.
--login	RED	n/a	Interactive OAuth flow deferred; chimera auth login covers it.

Slash commands (REPL)

The upstream's slash palette is intentionally small. Weasel matches the small set and skips chrome that does not apply (no themes, no terminal-title rewrite).

Upstream slash	Weasel status	Notes
/help	GREEN	Lists registered commands and shortcuts.
/exit (/quit, /q)	GREEN	Graceful shutdown.
/model	GREEN	Cycle through --models <list>.
/cost	GREEN	Per-session cost rollup.
/clear	GREEN	Reset context, keep provider.
/sessions	GREEN	List + resume.
/extensions	GREEN	List loaded extensions, allow / block.
/compact	GREEN	Manual compaction.
/login	RED	OAuth deferred.
/theme	RED	Out of scope.
/agent (subagents)	RED	Intentionally not shipped — install an extension.
/plan (plan mode)	RED	Intentionally not shipped — use a prompt template.

Extensions

The upstream's extension contract — auto-discover .{js,ts} files under an extensions/ directory, register tools / hooks / slash commands — is mirrored, with Python added as a first-class language.

Upstream capability	Weasel status	Notes
Auto-discovery	GREEN	.weasel/extensions/ + ~/.weasel/extensions/.
TS / JS extensions	GREEN	Subprocess via Node, JSON-RPC over stdio. As of wave-9 close (W1/W9), the bridge in chimera/weasel/node_executor.py actually executes JS/TS-contributed tools — manifest-driven, CJS + ESM both supported, fail-open when Node is missing. Wave-9 close (W1/W9).
Python extensions	GREEN	Native via importlib. (Superset.)
Manifest schema	GREEN	manifest.json for directory extensions.
Tool registration	GREEN	@tool decorator (Python) / registerTool (TS).
Hook registration	GREEN	@hook("pre_tool_use") etc.
Slash registration	GREEN	@slash("/foo").
Prompt templates	GREEN	prompts/*.md rendered with Jinja2.
Per-extension permissions	GREEN	Manifest permissions block tightens only.
Allowlist on first run	GREEN	.weasel/settings.json records allowed extensions.
Marketplace / pi pkg add	RED	Use git clone / pip install for now.

SDK

The upstream's SDK exposes an Agent class consumed by integrators. Weasel ships the same shape with both sync and async forms, plus a streaming generator API.

Upstream capability	Weasel status	Notes
Agent class	GREEN	chimera.weasel.sdk.Agent.
Sync run()	GREEN	Returns RunResult.
Async arun()	GREEN	Awaitable.
Streaming events	GREEN	agent.stream() async / agent.iter_stream() sync.
Mid-turn steering	GREEN	agent.steer(text).
Cancel	GREEN	agent.cancel().
Compaction	GREEN	agent.compact(strategy="summary").
Resume	GREEN	agent.resume(run_id).
Custom tools at runtime	GREEN	agent.register_tool(fn).
Custom hooks at runtime	GREEN	agent.register_hook(event, fn).
Custom event sink	GREEN	Agent(on_event=fn).
Permissions injection	GREEN	Agent(permissions=...).

RPC methods

Upstream's RPC mode exposes a JSON-RPC interface for process integration. Weasel mirrors the methods one-for-one and returns chimera.events-shaped event notifications.

Method	Weasel status
prompt	GREEN
steer	GREEN
cancel	GREEN
get_state	GREEN
compact	GREEN
list_sessions	GREEN
resume	GREEN
event notifications	GREEN

Error-code mapping (parse / invalid / cancelled / provider / permission) lives in modes.md.

Providers

Weasel reuses Chimera's full provider stack, so this is a superset of the upstream chain (which is hosted-first). The auto-fall-through to a local Ollama daemon is a weasel-specific addition for zero-config laptops.

Upstream provider	Weasel status	Notes
Anthropic	GREEN	Default for hosted; extended thinking, prompt cache.
OpenAI	GREEN	Streaming, reasoning-token tracking, JSON mode.
OpenRouter	GREEN	vendor/name routing rule.
Ollama	GREEN	Local + :cloud tags, keep_alive=60m.
llama.cpp	GREEN	Via OpenAI-compatible adapter + --base-url.
Modal-hosted	YELLOW	Programmatic only (no auto-detection).
Custom	GREEN	register_provider("name", factory).
Subscription auth (/login)	YELLOW	Device-flow OAuth via chimera.auth; CLI /login deferred.

Settings file

The upstream's settings file lives under .pi/settings.json. Weasel uses .weasel/settings.json. Keys map one-to-one where possible.

Upstream key	Weasel status	Notes
model	GREEN	Default model when no flag / env.
extensions.allowed	GREEN	Allowlist for unattended runs.
extensions.blocked	GREEN	Blocklist that shadows allowed.
permissions	GREEN	Mapped to chimera.permissions rules.
theme	GREEN	chimera/weasel/themes.py ships built-in default / dark / solarized palettes + REPL prompt-prefix bundles, with --theme <name> / $WEASEL_THEME selection and ~/.weasel/themes/ + .weasel/themes/ user/project overlays. Wave-9 close (W2/W9).
keybindings	RED	No custom keybindings.
compaction.threshold	YELLOW	Honored when present; default lives in chimera.compaction.
Prompt templates	GREEN	chimera/weasel/prompt_templates.py ships markdown-with-frontmatter system prompts via --prompt-template <name> / $WEASEL_PROMPT_TEMPLATE, same scope precedence as themes. Wave-9 close (W2/W9).

Counts

• Surfaces: 10 GREEN, 0 YELLOW, 0 RED of 10.
• CLI flags: 18 GREEN, 2 YELLOW, 1 RED of 21.
• Slash commands: 8 GREEN, 0 YELLOW, 4 RED of 12 (the four REDs are intentional design choices).
• Extension surface: 10 GREEN, 0 YELLOW, 1 RED of 11 (refreshed at wave-9 close — TS / JS execution promoted to GREEN via W1/W9's Node subprocess bridge).
• SDK surface: 12 GREEN, 0 YELLOW, 0 RED of 12.
• RPC methods: 8 GREEN of 8.
• Providers: 6 GREEN, 2 YELLOW, 0 RED of 8.
• Settings keys: 6 GREEN, 1 YELLOW, 1 RED of 8 (refreshed at wave-9 close — theme and prompt template rows promoted to GREEN via W2/W9's two new registries).

Wave-6 live verification: the GREEN counts above were spot-checked against chimera weasel --help, the 164 passing tests under tests/weasel/, the 9 source modules under chimera/weasel/, and the JSON-RPC round-trip + SDK demo at examples/weasel_sdk_quickstart.py. No row was downgraded by the wave-6 audit; weasel meets every contract above at the black-box level.

Chimera-only capabilities (do not regress)

Weasel inherits Chimera primitives the upstream does not have:

• Cooperative CancellationToken (true mid-turn cancel).
• MessageQueues for safe mid-turn steering.
• Loop detection (exact + pattern cycle).
• EventSourcedSession crash recovery + gap detection.
• FileAwareCompaction (file tracking across compaction).
• SessionTree in-place branching.
• RedactionMiddleware for ten secret patterns.
• CostTracker with cache + reasoning-token breakdown.
• 26-event EventBus with middleware.
• AgentConfig.from_markdown() for project / user / built-in registries (used by extensions that ship prompt-driven sub-roles).

Follow-up issues to file

1. chimera weasel /login — interactive OAuth flow.
2. chimera weasel --thinking <level> — first-class flag instead of env-var pass-through.
3. Marketplace command (chimera weasel ext install <git-url>).
4. Theme system parity (low priority — chrome only). Shipped at wave-9 close (W2/W9 — three built-in palettes plus the prompt-template registry). REPL wiring of the resolved theme stays as a downstream consumer follow-up.
5. Per-extension dependency resolution beyond depends_on (semver ranges, conflict detection).
6. RPC streaming back-pressure (drop / buffer policy when client reads slowly).
7. TS / JS extension tool execution. Shipped at wave-9 close (W1/W9 — chimera/weasel/node_executor.py).

How to use this matrix

When a user runs chimera weasel from a project that already contains a .pi/ settings or extensions directory, weasel does not automatically inherit it — the on-disk path is referenced as a migration target only. Mention upstream paths as a fact when helping users move; do not introduce an automatic ingest.

GREEN rows are expected to behave in lockstep with the upstream minimal harness at the black-box level. YELLOW rows degrade gracefully and emit a hint where the gap is user-visible. RED rows are not implemented, by design or by deferral; the table makes the reason explicit.

See also

• quickstart.md — short tour of the four modes.
• modes.md — long form on each mode.
• extensions.md — extension contract and examples.
• sdk.md — embedded Agent class.
• providers.md — provider chain.
• security-and-trademarks.md — trademark hygiene + security posture.

Cross-links

• Chimera architecture (8-phase map) — where the rows in this matrix live in the shared library.