callstack__agent-device/AGENTS.md

AGENTS.md

Minimal operating guide for AI coding agents in this repo.

Agent skills

Issue tracker

Issues and PRDs live in GitHub Issues for callstackincubator/agent-device. See docs/agents/issue-tracker.md.

Triage labels

Use the default Matt Pocock skills triage vocabulary: needs-triage, needs-info, ready-for-agent, ready-for-human, and wontfix. See docs/agents/triage-labels.md.

Domain docs

Single-context repo. Read CONTEXT.md for domain language and testing/architecture vocabulary, and docs/adr/ for accepted architecture decisions. See docs/agents/domain.md.

First 60 Seconds

• Classify task type:
  • Info-only (triage/review/questions/docs guidance): no code edits and no test runs unless explicitly requested.
  • Code change: make minimal scoped edits and run only required checks from Testing Matrix.
• State assumptions explicitly. If uncertain, ask.
• If the task touches tooling/builds/linting, read package.json and tsconfig*.json before source files.
• Prefer repo scripts over reconstructing command bundles by hand:
  • pnpm check:quick: lint + typecheck
  • pnpm check:tooling: lint + typecheck + build
  • pnpm check:unit: unit + smoke
  • pnpm check: full non-integration validation
• Read at most 3 files first:
  • owning handler/module
  • one shared helper used by that handler
  • one downstream platform file if needed
• Define verifiable success criteria before editing.
• Decide docs/skills impact up front.

Scope

• Solve issues with the smallest context read.
• Keep changes scoped to one command family or module group.
• Preserve daemon session semantics and platform behavior.
• Expand only when contracts cross module boundaries.
• Do not read both iOS and Android paths unless explicitly cross-platform.
• If requested fix expands beyond one command family/module group, stop and confirm before broadening scope.

Code Changes

• Minimum code that solves the problem. No speculative features.
• No abstractions for single-use code.
• Surgical edits only.
• Match existing style.
• Remove imports/variables YOUR changes made unused; do not clean unrelated dead code.
• Keep tests minimal: if TypeScript can enforce a contract or invalid shape, prefer a type-level check over duplicating that assertion in runtime tests.
• Keep modules small for agent context safety:
  • target <= 300 LOC per implementation file when practical.
  • if a file grows past 500 LOC, plan/extract focused submodules before adding new behavior.
  • exception: generated files, schema/fixture snapshots, and integration test aggregations.

Routing

• Keep src/daemon.ts as a thin router.
• Keep command names and daemon routing groups centralized in src/command-catalog.ts; do not re-create command string sets in handlers or request policy modules.
• Keep CLI/client positional grammar in src/command-codecs.ts and its src/command-codecs/* command-family modules. CLI commands, typed client methods, and daemon interaction adapters should reuse these codecs instead of duplicating selector/ref/positionals parsing.
• Keep src/daemon/request-router.ts as request orchestration: auth, diagnostics scope, request admission, locking, handler chain, and fallback dispatch.
• Put request policies in focused request modules:
  • tenant/lease/selector/lock admission: src/daemon/request-admission.ts
  • artifact/error finalization: src/daemon/request-finalization.ts
  • request-scoped platform provider scoping: src/daemon/request-platform-providers.ts
  • generic fallback dispatch + action recording: src/daemon/request-generic-dispatch.ts
  • recording invalidation health: src/daemon/request-recording-health.ts
• Put command logic in handler modules:
  • session/apps/appstate/open/close/replay/logs: src/daemon/handlers/session.ts
  • click/fill/get/is: src/daemon/handlers/interaction.ts
  • snapshot/wait/alert/settings: src/daemon/handlers/snapshot.ts
  • find: src/daemon/handlers/find.ts
  • record/trace: src/daemon/handlers/record-trace.ts
• Generic passthrough (press/scroll/type) is daemon fallback only after handlers return null.

Toolchain Snapshot

• Package manager: pnpm only. Do not add or restore package-lock.json.
• Runtime baseline is Node >= 22. Prefer built-in Node APIs such as global fetch, Web Streams, and AbortSignal.timeout over compatibility wrappers unless the surrounding code needs a lower-level transport.
• Lint/format stack is OXC:
  • config: .oxlintrc.json, .oxfmtrc.json
• TypeScript is strict enough to surface dead code early: strict, isolatedModules, noUnusedLocals, and noUnusedParameters are enabled.
• The repo emits with rslib, not tsc. If declaration generation fails, inspect tsconfig.lib.json first.
• tsconfig.lib.json needs an explicit rootDir: "./src" for declaration layout.
• Use the aggregate scripts in package.json when possible; they encode the expected validation bundles better than ad hoc command lists.

Cheap Exploration

• Prefer these first-pass commands over broader reads:
  • rg -n "<symbol|command|flag>" src test
  • rg --files src/daemon/handlers src/platforms/ios src/platforms/android
  • git diff -- <path> for active-branch context
  • read .oxlintrc.json before treating lint output as source-level bugs
• If build/type errors mention declaration generation, inspect tsconfig.lib.json before reading platform code.
• If lint failures appear after toolchain edits, check whether the rule is from eslint/*, typescript/*, import/*, or node/* in .oxlintrc.json before assuming source bugs.

Command Family Lookup

• logs: src/daemon/handlers/session.ts -> src/daemon/app-log.ts -> src/daemon/handlers/__tests__/session.test.ts
• open/close/replay/apps/appstate: src/daemon/handlers/session.ts -> src/daemon/session-store.ts -> src/daemon/handlers/__tests__/session.test.ts
• click/fill/get/is: src/daemon/handlers/interaction.ts -> src/daemon/selectors.ts -> src/daemon/handlers/__tests__/interaction.test.ts
• snapshot/wait/settings/alert: src/daemon/handlers/snapshot.ts -> src/daemon/snapshot-processing.ts -> src/daemon/handlers/__tests__/snapshot-handler.test.ts
• record/trace: src/daemon/handlers/record-trace.ts -> src/platforms/ios/runner-client.ts -> src/daemon/handlers/__tests__/record-trace.test.ts

iOS Runner Seams

• Keep dependency direction clean:
  • runner-client.ts: command execution + retry behavior
  • runner-transport.ts: connection/probing/HTTP transport
  • runner-contract.ts: shared RunnerCommand type and runner connect/error helpers
  • runner-session.ts: session lifecycle and request/response execution
  • runner-xctestrun.ts: xctestrun preparation/build/cache logic
• runner-transport.ts must not import back from runner-client.ts.
• If changing runner connect errors, retry policy, or command typing, start in src/platforms/ios/runner-contract.ts before touching client/transport files.

Adding a New CLI Flag

A new snapshot/command flag touches up to 7 files in a fixed order. Follow this checklist:

1. src/utils/command-schema.ts: add to CliFlags type, FLAG_DEFINITIONS array, and the relevant *_FLAGS constant (e.g. SNAPSHOT_FLAGS). Update the command's usageOverride string.
2. src/utils/snapshot.ts (or the relevant options type): add to SnapshotOptions or equivalent.
3. src/client-types.ts: add to CaptureSnapshotOptions (or equivalent public options type) and InternalRequestOptions.
4. src/client-normalizers.ts: map the public option name to the internal flag name in buildFlags.
5. src/daemon/context.ts: add to DaemonCommandContext type and contextFromFlags function.
6. src/core/dispatch-context.ts: add to DispatchContext when the flag flows into platform dispatch, then thread it through the relevant dispatcher module.
7. src/cli/commands/<command>.ts: pass the flag from flags.* to the client call.

Command-only flags (like find --first) that don't flow to the platform layer only need steps 1 and the handler file.

Hard Rules

• Use process helpers from src/utils/exec.ts for TypeScript process execution: runCmd, runCmdStreaming, runCmdSync, runCmdBackground, and runCmdDetached. Do not import raw spawn/spawnSync outside src/utils/exec.ts; add or extend an exec helper instead. Plain .mjs packaging fixtures that cannot import TypeScript helpers should keep child-process usage local and prefer execFile/execFileSync over spawn.
• Use daemon session flow for interactions (open before interactions, close after).
• Use keyboard dismiss for iOS keyboard dismissal; it may tap safe native controls such as Done but must not fall back to system back navigation.
• Do not remove shared snapshot/session model behavior without full migration.
• Command/device support must come from src/core/capabilities.ts.
• Apple-family target changes must keep src/utils/device.ts, src/core/capabilities.ts, src/core/dispatch-resolve.ts, src/platforms/ios/devices.ts, and src/platforms/ios/runner-xctestrun.ts in sync.
• iOS simulator-set scoping is iOS-specific: do not let iosSimulatorDeviceSet hide the host macOS desktop target when --platform macos or --target desktop is requested.
• If Swift runner code changes, run pnpm build:xcuitest.
• Use inferFillText and uniqueStrings from src/daemon/action-utils.ts.
• Use evaluateIsPredicate from src/daemon/is-predicates.ts for assertion logic.

Logs Contract

• Logs backend/source of truth is src/daemon/app-log.ts.
• session.ts should orchestrate only (start/stop/path/doctor/mark), not duplicate backend logic.
• Preserve external grep/tail workflow in docs/skills.

Diagnostics & Errors

• Diagnostics source of truth: src/utils/diagnostics.ts
  • withDiagnosticsScope, emitDiagnostic, withDiagnosticTimer, flushDiagnosticsToSessionFile
• Do not add ad-hoc stderr/file logging where diagnostics helpers apply.
• Normalize user-facing failures via src/utils/errors.ts (normalizeError).
• Failure payload contract: code, message, hint, diagnosticId, logPath, details.
• Preserve hint, diagnosticId, logPath when wrapping/rethrowing errors.
• --debug is canonical; --verbose is backward-compatible alias.
• Keep redaction centralized in diagnostics helpers.

Optional Optimizations

• Treat optional optimization calls such as cache/preflight/probe requests as best-effort unless the feature contract says they are required. If an optimization fails, times out, returns non-OK, or returns an unusable shape, prefer falling back to the existing required command path.
• Keep optimization timeouts shorter than the underlying operation timeout. A preflight should not consume the full budget for a later upload or command.

React Native Verification

• After changing runtime code exercised through bin/agent-device.mjs or the daemon, run pnpm build and pnpm clean:daemon before manual device verification so snapshots use current dist output.
• For Android RN/Expo/dev-client apps connected to any local Metro port, adb reverse tcp:<port> tcp:<port> is harmless and should be run before opening the app or URL on the emulator/device.

Selector System Rules

• Interaction commands (click, fill, get, is) and wait accept selectors and @ref.
• Pipeline: parse -> resolve -> act -> record selectorChain -> heal on replay.
• Keep selector parsing/matching in src/daemon/selectors.ts.
• Call buildSelectorChainForNode after resolving target nodes.
• New element-targeting interactions must support selector + @ref, record selectorChain, and hook replay healing (healReplayAction in session.ts + selector helpers in session-replay-heal.ts).
• New selector keys remain centralized in selectors.ts.
• New is predicates belong in evaluateIsPredicate.
• On macOS, snapshot rects are absolute in window space. Point-based runner interactions must translate through the interaction root frame; do not assume app-origin (0,0) coordinates.
• Prefer selector or @ref interactions over raw x/y commands in tests and docs, especially on macOS where window position can vary across runs.

Shared Test Utilities

• Before writing a new test, check src/__tests__/test-utils/ for existing helpers:
  • device-fixtures.ts: canonical DeviceInfo constants (ANDROID_EMULATOR, IOS_SIMULATOR, IOS_DEVICE, MACOS_DEVICE, LINUX_DEVICE, etc.)
  • session-factories.ts: makeSession, makeIosSession, makeAndroidSession, makeMacOsSession
  • store-factory.ts: makeSessionStore (creates temp SessionStore instances)
  • snapshot-builders.ts: buildNodes, makeSnapshotState
  • mocked-binaries.ts: withMockedAdb, withMockedXcrun (stub CLI binaries for dispatch tests)
• Use import { ... } from '<relative-path>/__tests__/test-utils/index.ts' for convenient barrel imports.
• Prefer shared fixtures over inlining new DeviceInfo or SessionState objects in tests.
• Do not duplicate makeSessionStore, makeSession, or device constants when a shared helper already exists.

Testing Matrix

• Docs/skills only: no tests required unless a more specific rule below applies.
• CLI help/guidance changes in src/utils/command-schema.ts: run pnpm exec vitest run src/utils/__tests__/args.test.ts.
• SkillGym prompt/assertion changes: run the touched --case checks. For broad validation, use pnpm test:skillgym; use --tag fixture-smoke or --tag skill-guidance when validating one suite group.
• Non-TS, no behavior impact: no tests unless requested.
• Keep tests behavioral; do not assert shapes or cases TypeScript already proves.
• Any TS change: pnpm typecheck or pnpm check:quick.
• Tooling/config change (package.json, tsconfig*.json, .oxlintrc.json, .oxfmtrc.json): pnpm check:tooling.
• Daemon handler/shared module change: pnpm check:unit.
• iOS runner/Swift change: pnpm build:xcuitest.
• Cross-platform behavior change: run pnpm test:integration.
• Any change in: src/, test/, skills/: pnpm format.

Token Guardrails

• Do not read unrelated files once owning module is identified.
• Do not run integration tests by default.
• Do not inspect both iOS and Android codepaths unless task requires both.
• Prefer targeted git diff -- <paths> over broad file reads during review.
• Prefer snapshot -i, find, and scoped selectors over repeated full snapshot dumps when exploring Apple desktop UIs.
• Keep PR summaries short and scoped.

Common Mistakes

• Adding command logic to src/daemon.ts instead of handlers.
• Adding capability checks outside src/core/capabilities.ts.
• Inlining is predicate logic in handlers.
• Returning non-normalized user-facing errors.
• Duplicating logs backend logic in handlers instead of src/daemon/app-log.ts.
• Growing src/daemon/handlers/session.ts or src/platforms/ios/apps.ts further without extracting Apple-family/macOS-specific helpers first.
• Reintroducing an npm lockfile or assuming ESLint/Prettier still exist in this repo.
• Changing tsconfig.lib.json/build tooling without running pnpm check:tooling; declaration generation is stricter than tsc --noEmit.

Docs & Skills

• Versioned CLI help is the agent-facing source of truth. Put workflow guidance in src/utils/command-schema.ts help topics and assert important copy in src/utils/__tests__/args.test.ts.
• Skills are thin routers. Keep skills/**/SKILL.md focused on when to use the skill, version gating, which agent-device help <topic> page to read, and a short default loop. Do not duplicate full CLI manuals in skills.
• For behavior/CLI surface changes, update the versioned help instructions in src/utils/command-schema.ts and assert important help copy in src/utils/__tests__/args.test.ts. Also update README.md and relevant website/docs/** when user-facing docs need it.
• For behavior/CLI surface changes and command-planning guidance changes, write or update a SkillGym case in test/skillgym/suites/agent-device-smoke-suite.ts that captures the expected agent command plan.
• Do not update skills/**/SKILL.md for command behavior or workflow guidance unless the user explicitly asks; skills must route to versioned CLI help instead of carrying behavior details.
• Keep SkillGym cases behavioral and command-planning oriented. Prefer prompts that assert the user-visible contract and expected command family over brittle exact output, but forbid known bad patterns.
• Build before SkillGym when local CLI help is needed: pnpm build, then pnpm exec skillgym run ... --case <id>.
• Run SkillGym broad validation with pnpm test:skillgym; use v0.8 --tag filters for focused suite groups.
• Preserve current high-value workflow guidance:
  • iOS Expo Go dogfood: prefer agent-device open "Expo Go" <url> --platform ios when the shell is known, then snapshot -i to confirm the project UI rather than the runner splash.
  • keyboard dismiss is the preferred iOS keyboard-dismissal path before manually pressing visible keyboard controls such as Done; it remains best-effort and can report unsupported layouts explicitly.
  • Empty replacement is not a supported clear-field command; do not document or test fill <target> "" as clearing. Prefer visible clear/reset controls or report the tool gap.
  • Mutating commands against one session must run serially. Parallelize only read-only commands or commands on separate sessions/devices.
• In final summaries, state whether docs/skills were updated; if not, explain why.

When Blocked

• If blocked by network/device/auth/permissions, stop and report:
  • blocker
  • why it blocks completion
  • exact next command/action needed to unblock

Key Files

• CLI parse + formatting: src/bin.ts, src/cli.ts, src/utils/args.ts
• Daemon client transport: src/daemon-client.ts
• Daemon state/store: src/daemon/session-store.ts
• Selector DSL and matching: src/daemon/selectors.ts
• is predicate evaluation: src/daemon/is-predicates.ts
• Shared action helpers: src/daemon/action-utils.ts
• Snapshot shaping + labels: src/daemon/snapshot-processing.ts
• Handler context helpers: src/daemon/context.ts, src/daemon/device-ready.ts
• Request routing/policy: src/daemon/request-router.ts, src/daemon/request-admission.ts, src/daemon/request-generic-dispatch.ts
• Dispatcher + capability map: src/core/dispatch.ts, src/core/dispatch-context.ts, src/core/dispatch-interactions.ts, src/core/capabilities.ts
• Command catalog + positional codecs: src/command-catalog.ts, src/command-codecs.ts, src/command-codecs/*
• Platform backends: src/platforms/ios/*, ios-runner/*, src/platforms/android/*

Pull Requests

• Before opening PR: ensure no conflict markers/unmerged paths.
• Commit messages and PR titles should use conventional prefixes such as feat:, fix:, chore:, perf:, refactor:, docs:, test:, build:, or ci: as appropriate.
• Do not use bracketed automation prefixes such as [codex] or similar bot tags in commit messages or PR titles.
• Open a ready-for-review PR by default. Use a draft PR only when the user explicitly asks for one or the work is intentionally incomplete.
• Run required checks for touched scope from Testing Matrix.
• PR body must be short and include:
  • ## Summary: describe the user-visible or reviewer-relevant change as before/after when useful, and include the issue closed by the PR using Closes #123 when applicable.
  • ## Validation: answer this prompt in concise prose: "How did you verify the change, and what passed or changed on screen?" Prefer evidence over command dumps; mention the relevant check category or scenario, and include screenshots when visual/UI behavior is relevant.
• Call out known gaps/follow-ups explicitly.
• Include touched-file count and note if scope expanded beyond initial command family.

Priority Order

• When guidance conflicts, apply in this order: Hard Rules -> Scope -> Testing Matrix -> style/preferences.