feat(agents): add copilot adapter

[yyovil]

Adds the copilot harness, stacked on #119 (agent platform). Adapter package + Constructors() registration + resolver test. Includes its own activity deriver.

🤖 Generated with Claude Code

Stack

1. feat(agents): agent platform — registry, activity hooks, harness allowlist #119
2. feat(agents): add grok adapter #120
3. feat(agents): add droid adapter #121
4. feat(agents): add amp adapter #122
5. feat(agents): add agy adapter #123
6. feat(agents): add crush adapter #124
7. feat(agents): add aider adapter #125
8. feat(agents): add cursor adapter #126
9. feat(agents): add qwen adapter #127
10. feat(agents): add copilot adapter #128 👈 current
11. feat(agents): add goose adapter #129
12. feat(agents): add auggie adapter #130
13. feat(agents): add continue adapter #131
14. feat(agents): add devin adapter #132
15. feat(agents): add cline adapter #133
16. feat(agents): add kimi adapter #134
17. feat(agents): add kiro adapter #135
18. feat(agents): add kilocode adapter #136
19. feat(agents): add vibe adapter #137
20. feat(agents): add pi adapter #138
21. feat(agents): add autohand adapter #139

[greptile-apps]

Greptile Summary

Adds the GitHub Copilot CLI agent adapter: a new copilot package with binary resolution, headless session launch/restore, workspace-local hook install/uninstall, and an activity deriver, all wired into the existing registry and dispatch table.

• copilot/copilot.go: Plugin implementing adapters.Adapter + ports.Agent; resolves the copilot binary once per lifetime and maps AO permission modes onto Copilot CLI approval flags (--allow-tool write, --allow-all-tools, --allow-all).
• copilot/hooks.go: Manages .github/hooks/ao.json — install, uninstall, idempotency, and atomic write — wired to four Copilot lifecycle events (sessionStart, userPromptSubmitted, permissionRequest, agentStop).
• copilot/activity.go: DeriveActivityState maps the four hook sub-commands onto ActivityActive, ActivityIdle, and ActivityWaitingInput.

Confidence Score: 4/5

Safe to merge with one fix: the local atomicWriteFile in hooks.go is missing a Sync call, which weakens its crash-safety guarantee relative to the shared hookutil version.

The adapter is well-structured and thoroughly tested. The one issue is that the local atomicWriteFile in copilot/hooks.go omits the tmp.Sync() step that hookutil.AtomicWriteFile includes, meaning a crash after Close() but before the OS flushes buffers could corrupt the hooks file and silently disable all Copilot hooks. The fix is a one-liner and the rest of the adapter is clean.

backend/internal/adapters/agent/copilot/hooks.go — the atomicWriteFile implementation needs a Sync call to match the shared hookutil version.

Important Files Changed

Filename	Overview
backend/internal/adapters/agent/copilot/hooks.go	New file. Implements Copilot hook install/uninstall/check. Has its own atomicWriteFile that is missing the tmp.Sync() call present in the shared hookutil.AtomicWriteFile, reducing crash-safety guarantees compared to other adapters.
backend/internal/adapters/agent/copilot/copilot.go	New file. Core adapter: binary resolution with once-per-lifetime caching, launch/restore command building, and session info. Logic is clean; noted limitations (nvm path, fallback caching) were flagged in previous review rounds.
backend/internal/adapters/agent/copilot/activity.go	New file. Simple, well-documented event-to-activity-state mapper. No issues found.
backend/internal/adapters/agent/copilot/copilot_test.go	New file. Good test coverage: launch/restore command building, permission mode mapping, hook install/uninstall idempotency, user-hook preservation, and activity deriver exhaustive table test.
backend/internal/adapters/agent/activitydispatch/dispatch.go	Trivial one-line addition registering copilot.DeriveActivityState in the dispatch map. Correct.
backend/internal/adapters/agent/registry/registry.go	Trivial one-line addition adding copilot.New() to Constructors(). Correct.
backend/internal/daemon/wiring_test.go	Adds HarnessCopilot → "copilot" resolver test case. Correct integration smoke test.

Sequence Diagram

sequenceDiagram
    participant AO as AO Daemon
    participant Plugin as copilot.Plugin
    participant FS as Filesystem
    participant Copilot as Copilot CLI

    AO->>Plugin: GetAgentHooks(cfg)
    Plugin->>FS: readCopilotHooks(.github/hooks/ao.json)
    FS-->>Plugin: copilotHookFile (or empty)
    Plugin->>Plugin: merge copilotManagedHooks (idempotent)
    Plugin->>FS: atomicWriteFile (tmp → rename)
    FS-->>Plugin: ok

    AO->>Plugin: GetLaunchCommand(cfg)
    Plugin->>Plugin: copilotBinary() [resolve once, cache]
    Plugin-->>AO: ["copilot", "--allow-all-tools", "-p", prompt]

    AO->>Copilot: exec(launch command)
    Copilot-->>FS: fires sessionStart hook
    FS->>AO: ao hooks copilot session-start → ActivityActive

    Copilot-->>FS: fires permissionRequest hook
    FS->>AO: ao hooks copilot permission-request → ActivityWaitingInput

    Copilot-->>FS: fires agentStop hook
    FS->>AO: ao hooks copilot stop → ActivityIdle

    AO->>Plugin: GetRestoreCommand(cfg)
    Plugin-->>AO: ["copilot", "--allow-all-tools", "--resume", agentSessionID]
    AO->>Copilot: exec(restore command)

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[harshitsinghbhandari]

Verified upstream Copilot CLI docs and pushed one fix.

Findings re-verified against upstream docs

• ✅ Hook event keys MUST be camelCase per https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/use-hooks — documented events are sessionStart, sessionEnd, userPromptSubmitted, preToolUse, postToolUse, errorOccurred, agentStop. The branch already shipped with the first three correct names (sessionStart, userPromptSubmitted, agentStop) — no change needed there.
• ✅ permissionRequest is not a documented Copilot event — closest signal is preToolUse (fires before every tool invocation, including ones that would prompt for approval). Confirmed at https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-config-dir-reference too (no permission-related hook events listed; permission decisions live in permissions-config.json, not hooks).

Changes (f1f540d)

• backend/internal/adapters/agent/copilot/hooks.go:88 — {Event: "permissionRequest", …} → {Event: "preToolUse", …}; comment block above copilotManagedHooks now cites the upstream docs and documents the many-to-one collapse (AO sub-command stays permission-request; only the Copilot-facing JSON key changed).
• backend/internal/adapters/agent/copilot/activity.go:13-19 — docstring updated so the permissionRequest/preToolUse distinction matches reality.
• backend/internal/adapters/agent/copilot/copilot_test.go — added TestCopilotManagedHooksUseDocumentedEventNames as a tripwire pinning every JSON event key (sessionStart, userPromptSubmitted, preToolUse, agentStop) to its AO sub-command. Existing install/uninstall tests already iterate copilotManagedHooks, so they pick up the new key automatically.

Validation

• cd backend && go build ./... — clean
• cd backend && go test -race ./... — 797 passed in 50 packages (32 in copilot)

Pushed with --force-with-lease. No design changes; AO's internal ao hooks copilot <sub> vocabulary and the activity-state mapping are unchanged.

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