Fix Cursor session mis-identified as Claude Code

[ashtom]

https://entire.io/gh/entireio/cli/trails/269

Summary

When Cursor Agent forwards a single user prompt to both .cursor/hooks.json and .claude/settings.json, two entire hook processes can claim the same session_id with different agent_types. The loser's wrong agent_type can win the last write — entire status then shows e.g. Claude Code (composer-2) for a Cursor session.

Two layered defenses + repair on the next turn:

• SessionStart agent hint (first-writer-wins): the first agent to fire SessionStart writes <sessionID>.agent with O_CREATE|O_EXCL. Subsequent hooks for the same session see the existing file and no-op. InitializeSession reads this hint at TurnStart so the firing hook can't relabel a session that another agent already claimed.
• Transcript-path override (strongest signal): at TurnStart, if the transcript path lives inside another agent's GetSessionDir(repo), that agent wins regardless of which hook is firing or what the hint says. This same check (correctSessionAgentType) also runs each turn against existing sessions, so a session that was mis-attributed on the racing turn is corrected the moment a later turn's transcript points to the true owner.
• Forwarded-event filter: once state.AgentType is recorded, lifecycle events fired by other agents are skipped (SessionStart and TurnStart are exempt — they need to reach the setup paths to perform repair).

Concurrent InitializeSession calls for the same session_id are accepted (no per-session lock — see e983e08a for the rationale: in field logs Cursor IDE only forwards SessionStart/Stop, not UserPromptSubmit, so the race doesn't actually fire in practice; the transcript-path repair handles any case where it does).

The SessionStart banner is gated by a separate <sessionID>.banner marker so a non-HookResponseWriter agent (Cursor) winning the ownership race can't suppress the banner from a banner-capable agent firing SessionStart for the same session (e38f1c60).

Test plan

• mise run fmt clean
• mise run lint clean
• All unit tests pass — added TestAgentForTranscriptPath, TestPathHasDirPrefix_CaseSensitivity (Windows-aware), TestStoreAgentTypeHint_*, TestClaimSessionStartBanner_*, TestResolveSessionAgentType_*, TestCorrectSessionAgentType_*, TestInitializeSession_HintWinsRaceAtTurnStart, TestInitializeSession_TranscriptPathRepairsExistingState, TestInitializeSession_ConcurrentCallsConvergeToTranscriptOwner (also under -race), TestHandleLifecycleSessionStart_NonWriterClaimDoesNotSuppressBanner, TestHandleLifecycleSessionStart_BannerClaimedOnce
• mise run test:integration passes
• mise run test:e2e:canary passes (4/4)
• GOOS=windows go build ./... and go vet clean
• Verified live in entire-helpers repo: existing wrong session repaired itself on the next prompt via transcript-path override
• Verify on Linux/Windows (CI)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR addresses a race where Cursor and Claude Code hooks can both initialize the same session, causing the persisted AgentType to intermittently reflect the wrong agent in entire status. It adds multiple signals and serialization so concurrent hook processes converge on the correct session owner.

Changes:

• Add a first-writer-wins agent-type hint file (<sessionID>.agent) written on SessionStart and consumed during TurnStart.
• Resolve/repair session ownership using transcript-path ownership detection (AgentForTranscriptPath) and a corrective update path.
• Serialize concurrent InitializeSession calls via a per-session cross-platform file lock stored under <git-common-dir>/entire-locks/.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
cmd/entire/cli/strategy/session_state.go	Adds per-session lock acquisition and agent-type hint read/write/cleanup logic.
cmd/entire/cli/strategy/manual_commit_hooks.go	Resolves the owning agent at InitializeSession and corrects stored AgentType based on transcript-path evidence.
cmd/entire/cli/agent/registry.go	Adds transcript-path → agent ownership resolution via session-dir prefix matching.
cmd/entire/cli/lifecycle.go	Stores agent-type hint during SessionStart to establish first-writer ownership.
cmd/entire/cli/filelock/filelock.go	Introduces a small cross-platform exclusive file lock abstraction.
cmd/entire/cli/filelock/filelock_unix.go	Unix implementation using flock.
cmd/entire/cli/filelock/filelock_windows.go	Windows implementation using LockFileEx.
cmd/entire/cli/strategy/session_state_test.go	Adds tests for agent-type hint storage/behavior and cleanup.
cmd/entire/cli/strategy/agent_resolution_test.go	Adds tests for agent resolution priority and concurrent initialization convergence.
cmd/entire/cli/lifecycle_test.go	Adds tests ensuring SessionStart stores the agent-type hint and first-writer-wins behavior.
cmd/entire/cli/filelock/filelock_test.go	Adds serialization/idempotent release tests for the lock implementation.
cmd/entire/cli/agent/registry_test.go	Adds tests for transcript-path agent ownership and prefix-collision handling.

[Soph]

@BugBot review

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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