[outlier27-cell]

Problem

Refs #901. OpenPI has several versioned, owner-local persisted sidecars, but their existing fail-closed decoder rules were not inventoried together or covered by a focused Plan Mode contract test. The P0 scope is evidence only: Pi continues to own Session identity, transcripts, resume/fork behavior, and Session-file migrations.

Value

Makes the currently implemented legacy, malformed, and future-version handling reviewable without creating a second Session store, a global migration engine, runtime orchestration, or an automatic user-data migration.

Approach

• Add a source-pinned inventory of the existing OpenPI-owned decoder seams and their intentionally distinct safe outcomes.
• Add synthetic Plan Mode sidecar tests for exact-current, malformed, and future records.
• Index the validated record in docs/research/README.md.

No production decoder, schema, user data, Pi Session file, or runtime path changes.

Validation

• node --test --experimental-strip-types tests/extensions/plan-mode/persisted-state.test.ts tests/extensions/workflows/journal.test.ts (16 passing)
• node --test --experimental-strip-types tests/extensions/shared/setup-config.test.ts (passing)
• bun run check (completed locally without a reported check failure)
• git diff --check origin/main (passing)
• bun run test was started; its local aggregate run did not provide a final summary before the execution limit, and its log contains one unrelated existing failure: child tool cards equal the main public renderer chain, without changing execution. CI is the full-suite authority.

Impact

None for user-visible behavior, model-visible context/tools, runtime/lifecycle, persisted configuration/data, or compatibility. This PR adds only tests and a source-pinned research record; it performs no file migration or rewrite.

[outlier27-cell]

Status update for current head 4250766:\n\n- The branch is synchronized with main at 1366f6a; the P0 change remains limited to its original three files.\n- GitHub run 40163578886 is complete with all 18 checks successful, including Windows UI and the aggregation gates.\n\nThe existing review request remains in place; awaiting maintainer review.

[outlier27-cell]

Validation update for the current head:

• node --test --experimental-strip-types tests/extensions/plan-mode/persisted-state.test.ts tests/extensions/workflows/journal.test.ts: 16 passing.
• node --test --experimental-strip-types tests/extensions/shared/setup-config.test.ts: passing.
• bun run check and git diff --check origin/main: passing locally.

Hosted CI is terminal but not fully green: its only failing job is Windows UI, where tests/web/browser-workbar-lifecycle.spec.ts:120 timed out after 5 seconds. That file is not in this PR's diff (which is limited to the sidecar compatibility record and Plan Mode contract tests), so I have not expanded the P0 scope to modify unrelated UI behavior. No merge action is requested here; I will wait for review and the CI baseline-handling decision.

[outlier27-cell]

@tt-a1i @testikun 麻烦审核 #902。P0 范围已完成，本地定向验证与 bun run check 已通过。当前 Windows UI 及其聚合 CI 失败尚未证明由本 PR 引入，正等待维护者审核与 CI 基线决定。

[outlier27-cell]

Current status: the branch is synchronized with main at 1366f6a, and the P0 change remains unchanged. GitHub run 40163578886 completed with all 18 checks successful, including Windows UI and the aggregate gates. There are no unresolved review threads. Awaiting maintainer review.