feat(FN-5103): complete Step 7 — update docs and changeset

Fusion-Task-Id: FN-5103
Fusion-Task-Lineage: e4e4d9ba-4884-4feb-b18b-a30e799c3fb1

.changeset/fn-5103-rebase-landed-files-attribution.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Restrict rebase-strategy landed-files capture to task-attributable commits and annotate short-circuit/fallback metadata for downstream reconciliation and reporting.

AGENTS.md

@@ -201,6 +201,7 @@ Detailed mechanism logs live in `docs/architecture.md` and `docs/design/`. The c
 - **Meta-task auto-archive safety guards (FN-5064)**: `auto-archive-meta-resolved`/`auto-archive-meta-stalled` must skip archival (with `task:auto-archive-meta-*-skipped` audits) whenever guard checks detect substantive work signals such as unique branch commits, recent executor activity, pending `taskDoneRetryCount`, merge-in-progress state, or active worktree session.
 - **Scheduler fanout tiebreaker (FN-4969)**: within the same priority class, scheduler dispatch prefers runnable `todo` tasks with the highest active dependency-dependent fanout; `urgent` always outranks lower priorities regardless of fanout, and `overlapBlockedBy`/file-scope overlap blockers are excluded from unblock weight.
 - **In-review branch-binding self-heal (FN-5083)**: `reconcile-in-review-branch-rebind` runs after `reconcile-task-worktree-metadata` and before `reclaim-stale-active-branches`. It restores `task.branch` (and clears `task.worktree` for fresh acquisition) for `in-review` tasks when exactly one case-insensitive `fusion/<id>` candidate branch has unique commits versus the integration base. Ambiguous candidates emit `task:auto-rebind-skipped` (`reason: "ambiguous-candidates"`) and are never auto-resolved. Branch construction across executor/worktree-pool/worktree-acquisition/merger/self-healing canonicalizes to lowercase via `canonicalFusionBranchName`; `fn_task_done` wrong-branch checks now auto-canonicalize case-only mismatches and emit `branch:auto-canonicalize-case`.
+- **Landed-files attribution (FN-5103)**: Rebase-strategy `mergeDetails.landedFiles` / `filesChanged` / `insertions` / `deletions` are captured from task-attributable commits only via `filterFilesToOwnTaskCommits` (subject-prefix + trailer + bracket-prefix evidence), tagged `landedFilesAttributionRestricted: true`. Zero own commits → `landedFiles: []` and `noOpVerifiedShortCircuit: true`. Attribution-helper failures fall back to the unrestricted `rebaseBaseSha..sha` walk and set `landedFilesCaptureFallback: 'attribution-failed'`. Self-healing `recoverDoneTaskMergeMetadata` skips reconcile when `landedFilesAttributionRestricted` or `noOpVerifiedShortCircuit` is set so the narrower set is not overwritten with the full range. Squash-strategy capture is unchanged.
 
 ## Engine Process Rules
 
@@ -504,5 +505,6 @@ Reliability-layer changes are in scope. Interaction regression backstops live in
 - FN-4976 backstop: `packages/engine/src/__tests__/reliability-interactions/stale-self-owned-session-registry.test.ts` guards `cleanupConflictingWorktree` clearing stale same-task `activeSessionRegistry` entries before the FN-4811 foreign-owner check, while preserving refusal behavior for foreign owners and live same-task bindings.
 - FN-4999 backstop: `packages/engine/src/__tests__/reliability-interactions/completion-handoff-limbo.test.ts` covers the `recoverCompletionHandoffLimbo` sweep stage (grace window, active-task skip, merge-blocker guard, capped retries, and audit fan-out).
 - FN-5083 backstop: `packages/engine/src/__tests__/reliability-interactions/in-review-branch-rebind.test.ts` covers in-review branch rebind composition with metadata-cleared state, idempotent re-sweeps, and ambiguous-candidate skip behavior.
+- FN-5103 backstop: `packages/engine/src/__tests__/reliability-interactions/landed-files-attribution.test.ts` covers attribution-restricted rebase landed-files capture, verified-short-circuit zero-own-commit capture, and attribution-failure fallback composition.
 
 The auto-recovery dispatcher at `packages/engine/src/auto-recovery.ts` (FN-4533) composes on top of existing layers (FN-4500 fast-path, FN-4508 deterministic branch-conflict, FN-4499 bootstrap-misbinding, FN-4428 contamination, `mergeAuditAutoRecovery` Stages 1–5, self-healing) to handle six residual classes: file-scope violation at squash, branch misbinding / ghost worktree, verification-fix scope leak, contamination, `branch-conflict-unrecoverable` residuals, and room-post/message-send failures. Invocation is additive — no existing layer's behavior changes.

docs/storage.md

@@ -81,7 +81,9 @@ Important execution nuance:
 - `task.modifiedFiles` stores the executor's last captured worktree snapshot. During in-progress/in-review this is the primary fallback and may include files later reverted before merge or changed by verification rebuilds.
 - `task.mergeDetails.landedFiles` stores the authoritative landed file list on the merge target:
   - squash path: `git show --name-only --format= <commitSha>`
-  - rebase/cherry-pick path: `git diff --name-only <rebaseBaseSha>..<commitSha>`
+  - rebase/cherry-pick path: union of files from task-attributable commits returned by `filterFilesToOwnTaskCommits` (`landedFilesAttributionRestricted: true`)
+  - attribution fallback path: if commit attribution fails, merger falls back to `git diff --name-only <rebaseBaseSha>..<commitSha>` and sets `landedFilesCaptureFallback: "attribution-failed"`
+- `mergeDetails.noOpVerifiedShortCircuit` marks rebase captures where zero commits are attributable to the task (`landedFiles: []`, stats zero); this indicates the branch's work was already on main.
 - After merge (and during self-healing reconciliation), Fusion updates `task.modifiedFiles` to match `landedFiles` when the landed set is available and non-empty.
 - Consumer guidance:
   - done tasks: prefer `mergeDetails.landedFiles`