In hooks/tsup.config.ts, add an esbuild plugin (externalize-sibling-hooks) that marks sibling ./*.mjs imports as external before tsup's noExternal catch-all runs. The previous config used noExternal: [/.*/] which overrode the external array, causing sibling hooks to be inlined with their side-effecting isMainModule() guards — producing invalid concatenated JSON output like "{}{}". The fix uses build.onResolve to intercept ./foo.mjs imports matching the hookExternalSet and return { external: true }. npm dependencies (minisearch, etc.) remain bundled inline.
In hooks/src/user-prompt-submit-skill-inject.mts line 581, change the lexical check from process.env.VERCEL_PLUGIN_LEXICAL_PROMPT === "1" to !== "0" so lexical stemmer fallback is on by default. Update the CLAUDE.md env var table to show default as "on" with "0" to disable.
Rebuild all compiled hooks via bun run build:hooks.
Instead of injecting the full SKILL.md body as additionalContext, inject
"You must run the Skill(<name>) tool." — a more conventional way of
telling the agent to use the Skill tool for context loading.
New ai-generation-persistence skill (priority 6) injects guidance for treating
AI generations as first-class persistent resources — unique IDs, addressable
URLs, database/Blob storage, cost tracking, and generate-then-redirect UX
patterns. Triggers on AI SDK imports and broad prompt signals.
New verification skill added. Updated ecosystem graph, catalog, manifest,
fixtures, and snapshots.
Parallel PreToolUse hooks were racing on the same seen-skills file, causing 2-6x
duplicate injections. UserPromptSubmit hook didn't share dedup state at all.
Fix by implementing atomic per-skill claim files (Oracle session: fix-dedup-race-condition-plan):
1. In hooks/src/hook-env.mts, add tryClaimSessionKey(sessionId, kind, key) using
openSync(path, 'wx') for atomic exclusive create. Add listSessionKeys() to read
claim dir, syncSessionFileFromClaims() to derive the txt snapshot, and
removeSessionClaimDir() for cleanup. Claim files live in
<tmpdir>/vercel-plugin-<sessionId>-seen-skills.d/<skill-name>.
2. In hooks/src/patterns.mts, add mergeSeenSkillStates(...values) to union env var,
session file, and claim dir state. Add serializeSeenSkills(set) helper.
3. In hooks/src/pretooluse-skill-inject.mts, load merged state from env+file+claims.
Before injecting each skill, call tryClaimSessionKey — first process wins, others
get EEXIST and skip. Use same claim path for once-only keys (agent-browser warning,
vercel-env-help). Pass sessionId through InjectOptions.
4. In hooks/src/user-prompt-submit-skill-inject.mts, preserve sessionId from parsed
input, load merged seen state, pass sessionId to injection flow so it uses the
shared claim backend. Skills injected via promptSignals now visible to PreToolUse.
5. In hooks/src/session-end-cleanup.mts, add rmSync deletion of claim directories.
6. Update CLAUDE.md dedup contract to document atomic claim mechanism.
7. Bump .plugin/plugin.json to 0.6.0, rebuild.
The 0.5.4 release added session-scoped temp files for dedup persistence, but this
was wrong — CLAUDE_ENV_FILE env vars ARE propagated to hook subprocesses by Claude
Code. The temp file approach littered tmpdir with hundreds of small files.
Revert to the original env-var-only mechanism:
1. Remove readSessionFile/writeSessionFile/dedupFilePath from hooks/src/hook-env.mts
2. Remove all writeSessionFile calls from pretooluse-skill-inject.mts — revert to
pure process.env.VERCEL_PLUGIN_SEEN_SKILLS = appendSeenSkill(...) pattern
3. Remove sessionId from InjectOptions and the injectSkills call site
4. Remove sessionId from posttooluse-validate.mts ParsedInput — revert
isAlreadyValidated/markValidated to pure env-var signatures
5. Revert all test expectations back to "env-var" and "memory-only" strategies
6. Restore CLAUDE.md dedup contract to env-var-only documentation
Skill dedup is completely broken because CLAUDE_ENV_FILE vars are only available to Bash
tool commands, not hook subprocesses. Each PreToolUse invocation starts a fresh Node.js
process that never sees VERCEL_PLUGIN_SEEN_SKILLS.
To fix this:
1. In hooks/src/hook-env.mts, add readSessionFile(sessionId, kind) and
writeSessionFile(sessionId, kind, value) helpers that read/write
/tmp/vercel-plugin-<sessionId>-<kind>.txt for persistent dedup state.
2. In hooks/src/pretooluse-skill-inject.mts, read seen skills from the session file
at startup using readSessionFile(sessionId, "seen-skills"). Add a persistSeen()
closure inside injectSkills() that calls both appendSeenSkill and writeSessionFile.
Replace all process.env.VERCEL_PLUGIN_SEEN_SKILLS = appendSeenSkill(...) calls with
persistSeen() or inline writeSessionFile calls. Add "file" as the primary dedup
strategy when session_id is present, falling back to "env-var" then "memory-only".
Pass sessionId through InjectOptions to injectSkills().
3. In hooks/src/posttooluse-validate.mts, add sessionId to ParsedInput and extract it
from input.session_id in parseInput(). Pass sessionId to isAlreadyValidated() and
markValidated(), which should read/write via readSessionFile/writeSessionFile for
the "validated-files" kind.
4. Update tests: pretooluse-skill-inject.test.ts — rename "no env var" test to expect
file-based dedup persistence, update strategy assertions from "env-var" to "file",
use omitSessionId for memory-only test. subagent-fresh-env.test.ts — use a fresh
session ID for subagent calls, update strategy expectations to "file".
session-timeline-subagent.test.ts — add sessionId option to runHookEnv, use a
different session ID for the subagent call.
5. Update CLAUDE.md dedup contract section to document file-based mechanism.
6. Bump .plugin/plugin.json version to 0.5.4, run bun run build.
- Replace tsc+cp+rm pipeline with tsup (7ms builds, no intermediate dir)
- tsup compiles hooks/src/*.mts directly to hooks/*.mjs
- tsconfig.json retained for type-checking only (noEmit)
- Remove all .sh references from tests, docs, and hooks.json
- Fix glob pattern test to handle tsup's output format
Hook source now lives in hooks/src/*.mts and compiles to hooks/*.mjs via tsc.
The formatOutput() return type is checked against SyncHookJSONOutput from
@anthropic-ai/claude-agent-sdk, preventing unknown fields in hookSpecificOutput
that Claude Code's strict Zod validation would silently reject.
Root cause: skillInjection metadata was a sibling key in hookSpecificOutput,
which Claude Code rejected as "Hook JSON output validation failed: Invalid input".
All skill injections were silently discarded. Now skillInjection metadata is
embedded as an HTML comment inside additionalContext.
- Add hooks/src/*.mts (TypeScript source for all 6 hook modules)
- Add hooks/tsconfig.json (strict, NodeNext, compiles .mts → .mjs)
- Add build:hooks script and pre-commit hook for auto-compilation
- Install @anthropic-ai/claude-agent-sdk as devDependency for types
- Bump plugin version to 0.4.0
Create hooks/vercel-config.mjs that reads vercel.json and maps top-level keys (rewrites, redirects, headers, crons, functions) to skill slugs, so skills are injected when the project uses those Vercel features.
Create hooks/logger.mjs with structured logging at four levels (off, summary, debug, trace) controlled by VERCEL_PLUGIN_LOG_LEVEL env var. Support legacy VERCEL_PLUGIN_DEBUG=1 mapping to debug level.
Create src/cli/explain.ts that takes a tool name and input JSON, runs the match engine, and prints which skills would fire and why. Create src/cli/index.ts as the CLI entry point. Create src/commands/doctor.ts for diagnosing plugin setup issues.
Create src/shared/logger.ts and src/shared/match-engine.ts as TypeScript versions of the shared utilities.
Create scripts/build-manifest.ts that reads all SKILL.md files, parses frontmatter, and generates generated/skill-manifest.json.
Add CLAUDE.md documenting the architecture, dedup contract, YAML parser quirks, test conventions, and log levels.
Add tests: tests/cli-explain.test.ts, tests/logger.test.ts, tests/vercel-config.test.ts, tests/snapshot-runner.test.ts with snapshot files in tests/snapshots/. Add test fixtures in tests/fixtures/. Update existing tests to copy new hook modules (logger.mjs, vercel-config.mjs) into temp dirs.
Update package.json with new bin entry and dependencies.
Rules (.mdc files) aren't supported by Claude Code's plugin system — they
were silently ignored. Move the ecosystem knowledge graph and all three
convention sets (Next.js 16, AI SDK v6, Vercel platform) into CLAUDE.md
so they're always loaded into context.
Also updates repo references from anthropics/open-plugin to
vercel-labs/vercel-plugin.
John Lindquist