feat(feed-hermit): feed-to-brief pipeline plugin

[gtapps]

Summary

New domain plugin feed-hermit (v0.1.0): a self-contained feed-to-brief pipeline — a curated source registry → fetch → score → write → deliver → archive → weekly-synthesis flow, with source-health analytics driven entirely by archive frontmatter. This is the seventh shipped plugin and the first "big pipeline" domain plugin, with the smallest dependency surface of the extraction series (core only).

Changes

• 8 skills — feed-brief (the 7-phase pipeline, --morning|--evening|--slot), weekly-digest, add-source, source-scout, source-health, story-arcs, deep-dive, hatch. Named feed-brief (not brief) to avoid trigger collision with core's status-summary brief skill.
• source-fetcher Haiku agent — raw web/RSS collection with an explicit tmp/feed-source-items-<slot>.json output contract.
• Scripts (zero runtime deps) — reddit-fetch.ts (unauthenticated hot.json by default, optional OAuth2 client-credentials path; exit 0 success / 1 error), validate-sources.ts (PostToolUse registry-table validator, keyed on feed-sources.md).
• fetch-guard.ts PreToolUse hook — WebFetch domain allowlist scraped from feed-sources.md + an infra list; blocks off-allowlist fetches (exit 2), fails open on unreadable registry. Prompt-injection containment shipped now rather than deferred.
• State-templates + hatch — seeds empty feed-sources.md/feed-categories.md/FEEDS.md at the project root (opt-in generic starter pack), registers morning/evening/weekly routines and a monthly source-scout scheduled check, appends the Feed Workflow block, adds tmp/ to .gitignore.
• docs/schema.md — the two data contracts (registry + archive frontmatter) documented verbatim, preserving the load-bearing sources_skipped vs sources_quiet distinction that powers source-health.
• Root wiring — marketplace entry, test-feed.yml CI (path-filtered, bun test), README + root CLAUDE.md updated to seven plugins.

Review + fixes folded in on this branch

• fetch-guard.ts — block reason now written to stderr (so the model receives it on exit 2), case-insensitive/lowercased host matching (an uppercase domain in the registry no longer blocks a legitimate source), and a SOURCES_FILE constant deduping the repeated filename literal.
• validate-sources.ts — colon-tolerant markdown separator regex, so alignment rows (:---:) no longer false-flag as invalid types.
• reddit-fetch.ts — clamp a non-positive limit to the default (was silently dropping posts / returning empty).
• CI — operator-facing state-templates reference docs via ${CLAUDE_PLUGIN_ROOT}/docs/... instead of bare docs/..., satisfying core's operator-doc-refs guard (this was the failing check).

Corrections vs the original extraction spec

• reddit_fetch.py's real contract is 0/1 (no exit-2 "unconfigured"); the TS port matches the live script, not its stale tests/docs.
• No bin/hermit-chrome-start exists in core — Chrome availability is treated as a deployment concern; sources skip gracefully when it's down. launch_chrome.py not ported.
• No core brief-block substrate (C4) or fetch-allowlist hook (C5) exists yet, so no dead brief-blocks/ template and no fetch_source_files meta key; both noted as planned core integrations. The fetch guard ships plugin-local until C5 lands.
• The Discord-reaction → brief-feedback producer lives in the channel layer (not shipped here); weekly-digest consumes it and degrades silently when absent.

Test plan

• cd plugins/feed-hermit && bun test → 52 pass, 0 fail (reddit-fetch exit-code contract via spawn, validate-sources cases, fetch-guard allow/block/fail-open, schema-contract, skill-structure).
• Core suite (plugins/claude-code-hermit) → green, incl. the marketplace↔dir bidirectional-sync invariant, operator-doc-refs, and skill-structure.
• bunx tsc --noEmit (repo-wide, strict) → 0 errors.
• Scoped grep sweep — briefing-hermit / news-brief / BRIEFING.md / any briefing inside plugins/feed-hermit/ → zero (the only surviving briefing in the repo is the generic core artifact-type, which is orthogonal).
• Hook smoke — fetch-guard.ts blocks an off-allowlist URL against a feed-sources.md allowlist; validate-sources.ts fires on a feed-sources.md edit and passes through a foreign sources.md.
• Not yet run: a live /feed-hermit:hatch smoke on a real target project.