callstack__agent-device/AGENTS.md

# AGENTS.md

`agent-device` is a CLI and daemon for automating Apple, Android, HarmonyOS, Vega, Linux, and web
targets. A long-lived daemon owns sessions; registry-derived commands route to platform runtimes.

This file contains repository-specific traps and invariants that are expensive to rediscover. Load
task procedures only when needed:

| When the task involves | Read |
| --- | --- |
| Domain vocabulary | `CONTEXT.md`, `docs/agents/domain.md` |
| Architecture decisions | `docs/adr/README.md` |
| Tests or gate selection | `docs/agents/testing.md` |
| Selector capture, polling, or interaction fast paths | `docs/agents/selector-capture.md` |
| Adding or changing a CLI flag | `docs/agents/cli-flags.md` |
| Opening or reviewing a PR | `docs/agents/pull-requests.md` |
| Migrating an ADR 0019 command | `docs/agents/adr-0019-unit.md` |
| Running against a real device | `docs/agents/device-verification.md` |
| Issues, PRDs, and triage labels | `docs/agents/issue-tracker.md`, `docs/agents/triage-labels.md` |
| Web backend setup or diagnostics | `docs/agents/web-backend.md` |

Versioned CLI help is the source of truth for command behavior. Start workflow planning with
`agent-device help workflow`, then use the relevant topic help.

## Incident-derived principles

- Guarantees erode at path boundaries. Classify every interaction dispatch path in
  `packages/contracts/src/interaction-guarantees.ts`; a registry claim is not proof that the native
  implementation satisfies the guarantee's definition.
- Delegation on error proves no success-path parity. A fast path may succeed on a candidate the
  shared rules would refuse.
- Prove that a code path can fire before measuring it. An A/B test with an unreachable arm is two
  green runs without evidence.
- A green regression test counts only after it has been observed red against the pre-fix code. Plant
  a violation for new structural gates and verify the gate names the invariant.
- Repair recurring failures at their owning interface with types, a registry, or one construction
  path. A custom guard that reconstructs another source of truth needs redesign, not another
  exception.
- Key behavior on typed reasons and details, never error text. Existing message sniffs are owned debt
  and must not be copied.
- Snapshot output is the token budget: do not add per-node metadata when response-level metadata can
  be emitted once. Append warnings through the shared response builder; never replace prior warnings.
- Before preserving a compatibility shape, run `git tag --contains <commit>`. Unreleased API has no
  external compatibility obligation.

## Declaration sites and enforcement

Read the declaration rather than maintaining a prose copy:

- commands and their surface, capability, batch, and timeout traits:
  `src/core/command-descriptor/registry.ts`
- daemon route ownership and request-policy traits: `src/daemon/daemon-command-registry.ts`
- interaction paths and guarantees: `packages/contracts/src/interaction-guarantees.ts`
- canonical command names: `src/command-catalog.ts`
- device capability admission: `src/core/capabilities.ts`

Shared selector parsing and matching belongs in `@agent-device/selectors`; request cancellation and
progress in `src/request`; cross-layer contracts in `src/contracts`; CLI flags in
`src/commands/cli-grammar`; cross-surface schema composition in `src/cli-schema`.

The enforced registries are self-declaring. A failing completeness, parity, coverage, timeout,
layering, or construction gate means the new cell or path is unclassified; do not suppress or
allowlist it. Interaction responses are built only through `buildInteractionResponseData`, and
cross-language rules change through golden tables under `contracts/fixtures/`.

## Hard repository rules

- Plain `.mjs` packaging fixtures that cannot import TypeScript execution helpers keep child-process
  use local and prefer `execFile`.
- Apple target changes keep the kernel device model, capability admission, dispatch resolution,
  Apple discovery, and xctestrun preparation in sync.
- iOS simulator-set scoping must never hide the host macOS desktop target.
- Skills may carry a minimal start/routing card; command semantics belong in versioned CLI help.
- Do not add compatibility or fallback behavior without explicit approval. Complete migrations and
  remove superseded paths.
- Keep changes within one command family or module group unless the task explicitly crosses a
  boundary. Platform-neutral work does not license inspecting every platform implementation.

## Module and test topology

- Name modules for the domain question they answer and colocate machine-readable claims with their
  enforcement. Internal barrels are legacy; add barrels only at package boundaries.
- Implementation files target at most 300 lines. Extract before adding behavior past 500 lines;
  files past 1,000 lines are architecture debt unless generated or fixture data.
- Tests mirror source topology one-to-one. Split a source module and its test together; do not add to
  the legacy `interaction.test.ts` or platform `index.test.ts` aggregations.
- Shared fixtures are named exports in a sibling fixture module, not repeated inline literals.
- `src/daemon/handlers/session.ts` is already over budget; extract the relevant platform-specific
  concept before adding behavior.

## Toolchain and worktree traps

- Use `pnpm`; never add `package-lock.json`. OXC owns lint and format. Run `pnpm format` for the
  repository, not a path-scoped formatter invocation.
- A fresh worktree requires `pnpm install --frozen-lockfile && pnpm build`. Until then package and
  optional-peer resolution may point at another checkout and produce false failures.
- Source-checkout daemon state is worktree-scoped, but devices are not. Use `pnpm daemon:state-dir`
  to inspect it and different devices for concurrent worktrees.
- Run one full gate per host at a time. Subprocess-backed tests under concurrent worktrees produce
  timeout-shaped contention failures.
- Before pushing, run `pnpm check:affected --run && git push`. Use `pnpm check` for broad refactors.
  GitHub remains authoritative for native, device, provider, and full-coverage lanes.
- The layering scan reads tracked files only. Stage a new module before trusting its result.
- Fallow baselines are path-keyed. Move the matching baseline entry when renaming a file; never bulk
  regenerate baselines to accept unrelated findings.
- The first Node process after a newly signed Apple runner launches may block during Gatekeeper
  verification. Warm it with a throwaway `node -e 0` before measuring.
- `DEVICE_IN_USE` normally means another session still owns the device. Follow the error's targeted
  `close --session` hint instead of debugging the daemon.
- A changing timeout failure set that passes in isolation is host contention. Reproduce the same
  test on `origin/main` under the same load before treating it as a regression.

## Runtime and diagnostics seams

The OS-neutral Apple runner lives under `src/platforms/apple/core/runner/`. For connection errors,
retry policy, or command typing, start at `runner-contract.ts`; transport stays below session/client
behavior, and xctestrun build/cache logic stays outside request execution.

Diagnostics use `src/utils/diagnostics.ts`. Request diagnostics belong in the session request log;
session artifact paths come from `src/daemon/session-store.ts`. App/device logs remain in `app.log`;
Apple runner and xcodebuild output remains in `runner.log`.

Normalize failures with `normalizeError` and preserve `hint`, `diagnosticId`, `logPath`, and typed
`details`. An interaction taking five seconds or more is a daemon-log question: inspect runner
restart, stale-session recovery, accessibility failure, transport retry, and timeout evidence.

Optional probes and caches are best-effort only when the feature contract says so. Their budgets
must be shorter than the required operation they precede.

## Selector and replay invariants

Element interactions support selector and `@ref`, then record a selector chain after resolution.
Replay failures may re-resolve that chain only to produce a ranked divergence suggestion; ADR 0012
retired silent script rewriting.

Selector keys stay centralized in `@agent-device/selectors`; `is` predicates use
`evaluateIsPredicate`. On macOS, snapshot rectangles are absolute in window space and point actions
translate through the interaction root frame. Prefer selector or ref tests over raw coordinates.

## Documentation ownership

Before adding guidance, decide whether the command surface, CLI grammar/help, MCP projection, daemon
runtime, ADR, or task procedure owns it. Link to executable registries instead of copying their
contents. Keep a sentence in this file only when no gate, lint rule, versioned help, ADR, or
decision-site comment can own it. `CONTEXT.md` is glossary-only: no implementation paths,
architecture decisions, migration state, or workflows.

Behavior changes update their owning help/metadata and user docs when relevant. In the final summary,
state whether docs or skills changed and why.