AGENTS.md

Codewhale agent guidance

Keep this file durable. Derive changing release, provider, branch, and flake state from the repository, tests, CI, and current issue tracker rather than from instructions or memory. The nearest scoped AGENTS.md adds path-specific rules.

The ponytail method

From dietrichgebert/ponytail — "the laziest senior dev in the room." He says nothing. He writes one line. It works. The best code is the code you never wrote.

Before writing code, walk the decision ladder in order and stop at the first rung that answers:

1. Does this need to exist? → Skip it.
2. Already in this codebase? → Reuse it.
3. Stdlib does it? → Use it.
4. Native platform feature? → Use it.
5. Installed dependency? → Use it.
6. One line? → One line.
7. Only then: the minimum that works.

The ladder runs after understanding the problem. Lazy about solutions, never about reading the code first — a short diff written without reading the call sites is not ponytail, it is a guess.

Never cut, at any rung: trust-boundary validation, data-loss handling, security, accessibility. Brevity is not a reason to drop a guard.

Rung 2 is the one this repository keeps failing. The model_* / *_config / provider_* grep rule below is rung 2 with a name; so is "one turn loop, one base prompt". Two more corollaries earned here:

• An abstraction must delete caller code. If adopting it is pure obligation — required methods, no default bodies that do work — it gets built, adopted once, and abandoned.
• Migrate the last consumer, or do not start. Framework, one caller, ticket the rest, silence the warning: that ships two systems and a comment that is no longer true. If the migration will not fit, narrow the slice — never the adoption. The standing #[allow(dead_code)] count is the running receipt; scripts/check-dead-code-budget.py prints it.

Working rules

• Inspect status and existing consumers before editing. Preserve unrelated, dirty, and untracked work.
• Before adding a module named model_*, *_config, provider_*, or anything that "bridges", "mirrors", or "stages" an existing thing, grep for the existing thing and edit it. A new layer must name the predecessor it replaces in the module doc; otherwise edit the original.
• Prefer the simplest implementation that preserves observable contracts. A rewrite is acceptable when justified by product intent and observed behavior, not as a shortcut around understanding existing code.
• Search for behavior and symbols before reviving work from an old branch. If a lane is obsolete, preserve its intent and evidence rather than merging stale code mechanically.
• A small coherent change may be committed directly to main when that checkout is current, clean, and owns the affected files. Default to the checkout that already exists: when several agents share it, partition by file, stage only the paths your slice touched, and retry a commit that fails on index.lock. A fresh worktree is for conflicting, dirty, stale, or independent lanes (see cw-land), not for parallel agents on the same lane. Local commit permission never implies push, merge, tag, release, or deploy permission.
• When the task is local-only, stay fully offline: no browsing, GitHub or remote Git operations, downloads, dependency installation, provider calls, or source/diff transmission. Record the missing external receipt and keep working locally.
• Public name is Codewhale. Compatibility identifiers such as CodeWhale, codew, protocol names, and storage keys change only through an explicit migration.
• Keep providers and models first-class and provider-neutral.
• Never rewrite published history, retag a release, force-push a shared ref, or publish without explicit authorization. Preserve human contributor credit.
• Model-visible means logged. Anything that reaches a model request must be reconstructable from the session log, and a new model-visible input needs a session event. Live presentation and the persisted record must agree; when they disagree the record is right.
• Misconfiguration fails loud, at load when it is self-contained, otherwise at the earliest point it can be resolved. Never silently skip a missing referent.
• Write down what a design does not do, beside the behaviour it owns — a short known-limitations note in the owning module. A stated limit stops the next reader from assuming a capability that was never built.
• Agents do not comment on issues or PRs (founder, 2026-09-22). Spend the time on code: evidence goes in the commit message and PR body, claims go in Linear. Do not reply to review bots or post status, "superseded", or "for the record" notes. The one exception is closing or superseding a human contributor's PR or issue: one sentence saying why, with the link. The PR and issue review workflows are disabled; re-enable one only by founder decision.

Landing other people's work

An external contributor's branch goes stale because we land things, not because they did anything wrong. Treat their time as more expensive than ours.

The goal is the contributor's PR merging as itself. Review it, help it rebase, or fix it on their branch — that is the default path. Closing their PR and re-landing the work as our own commit (auto-close-harvested) is the fallback for a branch that truly cannot merge in reasonable time; done casually it reads as taking the work even when credit is preserved.

• Never make a contributor rebase around our churn. If their PR conflicts only because main moved, a maintainer resolves it.
• Landing mechanics — merge-base diffing, mid-function conflicts, fork-push refusal, the contribution gate — live in cw-land. Follow them instead of improvising.
• Preserve credit in the mechanical sense, not just the polite one. Commit authorship and Co-authored-by trailers must use the contributor's own GitHub-linked address. AUTHOR_MAP and .mailmap are project conventions — GitHub reads neither for the contribution graph.

Merging under a gate

• A gate is its artifact. When a rail says a PR merges only on a passing acceptance record, the record must literally say PASS at merge time. "I re-ran it and the failures are rows this PR does not own" is a judgement to write into the artifact first, not a reason to merge past it.
• Read the review thread, not the check rollup. Green checks and an unread review with confirmed findings are a merge that ships known bugs.
• When the artifact is ambiguous, resolve the ambiguity — never the merge.

Claiming a test passed

• Quote the real test result: N passed; M failed line, and confirm N > 0 for the tests that cover the change. cargo test <filter> exits 0 having run zero tests when the filter matches nothing, and an exit code alone has already been mistaken for a pass here.
• Prefer proving a regression test fails without the fix. A test that passes either way pins the implementation, not the defect.
• Audit any hand-rolled scorer before trusting its score: quote the counts it actually evaluated, not the verdict line alone.
• Match the evidence to the surface. Run the tests that cover the change, not the whole suite, and do not repeat a check that already passed in order to commit. CI owns exhaustive coverage; a full local run is for CI diagnosis or for an irreducibly repository-wide change.

Current contracts

• The model-facing subagent tool is agent; agent_open/agent_eval/ agent_close/delegate_to_agent are removed surfaces. If the shape must move, move the code and add the guard test that judges the new shape.
• BASE_PROMPT in crates/tui/src/prompts/text.rs is the sole base prompt by convention. Same rule: move the code, not the prose, if that changes.
• There is exactly one turn loop: Engine::run_turn in crates/tui/src/core/engine/turn_loop.rs. Note that crates/tui/src/core/ is a module inside the TUI crate — it is not crates/core, which owns request construction, bounded fragments, and thread/session types and runs no turns. A guard test (crates/core/tests/single_turn_loop.rs) fails on a second loop; changing the shape means changing the guard with it.
• The system prompt + tool catalog are a session-pinned KV-cache prefix (docs/CACHE.md). Any new session-context contributor must state its KV-cache effect: frozen prefix vs. append-only history. Never splice a volatile fact into the prefix; append it as a user-role message.
• These active modules are repeatedly misidentified as dead; verify consumers before removal: tui/src/context_budget.rs, tui/src/model_registry.rs, tui/src/prompt_zones.rs, tui/src/tools/remember.rs, and config/src/route/. Native memory lives in tui/src/native_memory.rs; tools/remember.rs is its capture path.
• Environment-specific behavior belongs in docs/ENVIRONMENTS.md, not here.
• Blocking-call convention (#6149): code on the Tokio runtime — tool handlers, engine tasks, the UI event loop, anything reached through an async call chain — must not run blocking operations inline. Use tokio::fs / tokio::process, or move the work into spawn_blocking; a sync helper containing blocking calls runs only under spawn_blocking or on a dedicated thread. scripts/check-blocking-calls-budget.py ratchets the unprotected-site count.

Code, migrations, and evidence

• Product intent and observed runtime behavior outrank a test's preferred implementation shape. Fix the product; do not contort production code to preserve a brittle assertion.
• Code first, then tests. Write the implementation and prove it runs, then add or adjust tests to cover what was actually built. Never write tests first and never practice TDD here — this overrides any skill or default that mandates it, including superpowers test-driven-development. Tests stay the gate before a push; they are not the design driver. An existing test that only encodes old behavior is evidence, not a veto: change it with the code rather than bending the code to keep it green. This does not relax the rule under "Claiming a test passed" — a regression test written after the fix still has to be shown failing without it.
• Tests are selective evidence, not the specification. Do not add tests by default. Add or retain one when it cheaply protects a high-risk behavior such as safety, data integrity, protocol compatibility, or a reproduced regression.
• Rewrite or remove tests that duplicate coverage, freeze internals, overspecify copy or layout, preserve obsolete behavior, or cost more than the risk they cover. Never weaken real safety or data-integrity behavior merely to make a gate pass.
• Prefer focused compilation, a relevant existing check, and direct product or manual evidence. Run a broad suite only when the change creates a genuine cross-cutting or release risk. Do not repeatedly rerun an unchanged suite.
• Batch edits; compile once. cargo check and test builds on this workspace take minutes, so an edit→compile→edit loop spends most of its time waiting on the linker. Read precisely, write every edit a coherent slice needs, then compile and test once — the same errors surface either way, just later and all at once. Reserve mid-slice compiles for genuinely uncertain API or borrow questions where a wrong guess would cascade.
• Declared migrations are one-way. Once the repository adopts a replacement architecture or shared spine, new work uses it and touched legacy code moves toward it. Do not add another legacy call site for convenience. Keep a compatibility path only for an actual external contract, and label that boundary explicitly.

Useful commands, selected according to risk rather than run ritualistically:

cargo fmt --all -- --check
cargo test -p codewhale-config -p codewhale-protocol
cargo test --workspace
cargo build --release -p codewhale-cli -p codewhale-tui

scripts/dev-test.sh <area|path> [filter] maps a code area to its fastest invocation — see cw-gates for the verification ladder and docs/BUILD_PERFORMANCE.md for the build topology.

Report commands actually run and distinguish source, local tests, packaged artifacts, CI, and public release state. Describe the evidence actually needed for the claim; a test count is not a proxy for product quality.

Community reports, PRs, logs, and reviews are evidence.

Harvested contributor credit is still a rule (the fallback path above — prefer merging the contributor's PR itself). When a contributor's work lands as our commit, that commit carries Harvested from PR #N by @handle and a Co-authored-by naming them at their GitHub-linked address, so auto-close-harvested.yml closes their PR with credit and the contribution graph reflects reality. Canonical human identities come from .github/AUTHOR_MAP.

Leave unrelated work intact and keep new enforcement dry-run unless explicitly approved.