SessionStart dedup reset reads hook_event_name instead of source; regression fixtures mirror the mismatch

At commit 7b0a6f61b254b0149bb644cadfb588a5c46df0c2 (0.48.2), the Claude Code branch of hooks/src/session-start-seen-skills.mts:87 compares input.hook_event_name with clear/compact.

Claude Code's documented SessionStart payload uses hook_event_name: "SessionStart" and source: "clear" or "compact":
https://code.claude.com/docs/en/hooks#sessionstart-input

For example:

{"hook_event_name":"SessionStart","source":"clear","session_id":"synthetic-session"}

Static inspection shows that this payload cannot satisfy the current reset predicate. The generated hooks/session-start-seen-skills.mjs uses the same field. This is a schema mismatch found by inspection, not a report of an observed live-session failure.

Six fixtures in tests/session-start-seen-skills.test.ts at lines 136, 164, 190, 216, 256 and 294 currently put clear/compact/startup in hook_event_name, mirroring the implementation's mismatch.

Proposed change:

• Add source?: string to the input type and read input?.source ?? "" in the Claude branch.
• Preserve the Cursor early return and the existing nonempty session_id condition.
• Update the six fixtures to use hook_event_name: "SessionStart" with the corresponding source.
• Regenerate the distributed .mjs through the repository's build process.

Requested regression coverage:

• clear/compact reset only the intended session's dedup artifacts, preserve a different session's artifacts, and permit reinjection.
• startup/resume/fork/unknown or missing source preserve existing artifacts.
• Missing/empty session_id and legacy hook_event_name-only clear/compact payloads do not reset artifacts.
• Preserve Cursor behavior.

Validation so far: the existing two-hunk source patch matches the pinned source in an in-memory textual check; six fixture replacements were prepared as text. No repository scripts, hooks, build or tests were executed. The test helper runs the generated .mjs, so a source-only edit is insufficient for runtime validation. This fix makes an existing deletion branch reachable; its isolation and deletion scope should be verified before release.

Source:
https://github.com/vercel/vercel-plugin/blob/7b0a6f61b254b0149bb644cadfb588a5c46df0c2/hooks/src/session-start-seen-skills.mts#L87
Tests:
https://github.com/vercel/vercel-plugin/blob/7b0a6f61b254b0149bb644cadfb588a5c46df0c2/tests/session-start-seen-skills.test.ts#L136

Start with hooks/src/session-start-seen-skills.mts and tests/session-start-seen-skills.test.ts, then inspect the generated hooks/session-start-seen-skills.mjs used by the test helper. Run the repository's build process and focused tests; done means the six fixtures use the documented fields, regression coverage verifies session isolation and source handling, and generated output is updated without changing Cursor behavior.