test(scm): end-to-end integration coverage for SCM observer (#109)

[harshitsinghbhandari]

Summary

Adds the SCM observer end-to-end integration test from issue #109. Drives a real scmobserve.Observer.Poll against a real sqlite.Store, a real lifecycle.Manager wired with a recording messenger spy, and a canned observe/scm.Provider, asserting the full observation → reducer → store → messenger pipeline the daemon runs after the wiring landed in #114. New file is test-only: backend/internal/integration/scm_observer_test.go.

This is the regression guard for #108 — without it, a future change that re-introduces a nil messenger in daemon/lifecycle_wiring.go, drops the RepoOriginURL plumbing, or breaks the persisted dedup signature would land silently. Existing unit tests in observe/scm/observer_test.go and storage/sqlite/store/store_test.go cover each layer in isolation; nothing previously wired them together against a live SQLite + a live LCM.

Cases

Three table-driven subtests, each on its own tmpdir DB fixture so writes/messenger/lifecycle state never leak between them:

• CI-failing observation (acceptance items 1–4): the pr row reflects the observation (provider-neutral provider/host/repo columns, head_sha, semantic metadata_hash/ci_hash); pr_checks mirrors CI.Checks (name, status, commit hash, log tail); exactly one nudge reaches the messenger spy, addressed to the right session, body containing both the "CI is failing" cue and the failed-log tail. pr.last_nudge_signature is persisted, and a second identical Poll produces zero new nudges and leaves the signature unchanged (idempotency).
• Merged: true observation (acceptance item 5): the session row is MarkTerminated'd via the lifecycle reducer's merged branch, and no nudge is sent.
• Branch with no open PR (acceptance item 6): DetectPRByBranch returns ErrSCMNotFound, no pr row is written, and no nudge is sent.

Per the spec, the test drives Poll(ctx) directly with Config{Tick: time.Hour} rather than relying on the ticker.

Test plan

• cd backend && go build ./... — clean.
• cd backend && go test -race -run TestSCMObserverEndToEnd ./internal/integration/ — 3/3 pass.
• cd backend && go test -race ./... — full suite. One pre-existing environmental failure in internal/terminal (TestSessionStreamsRealZellijPane: zellij IPC socket path exceeds 103 bytes under macOS's /var/folders/... TMPDIR) is unrelated to this change and will pass under Linux CI.
• Remote GitHub CI (authoritative gate).

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR adds a single end-to-end integration test file (backend/internal/integration/scm_observer_test.go) that wires a real SQLite store, a real lifecycle manager with a messenger spy, and a canned SCM provider into the real SCM observer, then drives Observer.Poll directly to assert the full observation → reducer → store → messenger pipeline.

• Three table-driven sub-tests cover: CI-failing observation with dedup idempotency, merged-PR termination, and branch-with-no-PR no-op — each in an isolated tmpdir DB fixture.
• Tracing through the production code confirms all assertions are reachable and correct: the CI-failing nudge, the hash-match short-circuit on re-poll, MarkTerminated via the merged branch, and ErrSCMNotFound quiescing gracefully without writing any rows.

Confidence Score: 5/5

Safe to merge — test-only addition with no production code changes and no risk of regressions.

The change adds a single test file that exercises an existing wiring path. Tracing through the production code confirms every assertion is reachable: the hash-match short-circuit correctly prevents a second nudge on re-poll, MarkTerminated fires through the merged branch, and ErrSCMNotFound quiesces cleanly. Each sub-test uses its own isolated tmpdir DB so no state leaks between cases. No production logic is modified.

No files require special attention.

Important Files Changed

Filename	Overview
backend/internal/integration/scm_observer_test.go	New end-to-end integration test covering three SCM observer scenarios; wiring, assertions, and idempotency logic are all correct.

Sequence Diagram

sequenceDiagram
    participant T as Test
    participant O as Observer.Poll
    participant P as cannedSCMProvider
    participant DB as sqlite.Store
    participant LCM as lifecycle.Manager
    participant Spy as messengerSpy

    T->>O: Poll(ctx)
    O->>DB: ListAllSessions
    DB-->>O: [session]
    O->>P: DetectPRByBranch(repo, branch)
    P-->>O: SCMPRObservation
    O->>P: FetchPullRequests
    P-->>O: SCMObservation
    O->>DB: WriteSCMObservation(pendingPR)
    O->>LCM: ApplySCMObservation
    LCM->>Spy: Send nudge
    LCM->>DB: UpdatePRLastNudgeSignature
    O->>DB: WriteSCMObservation(finalPR)
    O-->>T: nil

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