feat: demonstration-fidelity skill + advisory hook (v6.2.0)

[intel352]

Summary

Closes a verification-theater gap reported in production: an agent writes real code, then "demonstrates" it with a demo that never executes the real artifact — reimplementing the logic, hard-coding the output, or rewriting it in another language. The demo proves nothing yet is presented as proof. This adds a harness-agnostic demonstration-fidelity skill (the load-bearing, all-harness layer) + an advisory write-time hook backstop (Claude/Codex/Cursor) + pipeline wiring.

Built by dogfooding the full autodev pipeline: brainstorming → 3× design adversarial review → writing-plans → 2× plan adversarial review → alignment-check → scope-lock → TDD execution → code review.

Design / Plan

• Design: docs/plans/2026-05-29-demonstration-fidelity-design.md (adversarial-review PASS rev3)
• Plan: docs/plans/2026-05-29-demonstration-fidelity.md (adversarial-review PASS rev2; alignment PASS; Locked)

Scope Manifest

• PR Count: 1 · Tasks: 8 · Status: Locked 2026-05-29T11:52:19Z
• This PR = the sole grouping row (Tasks 1–8).
• Out of scope: general anti-fabrication skill; blocking Stop interceptor; OpenCode per-tool hook port; user CLAUDE.md/AGENTS.md edits.

Changes

• skills/demonstration-fidelity/SKILL.md (host-neutral): a demo MUST execute the real artifact; output MUST be produced by that run. Forbids reimplementation / hard-coded output / artifact-stubbing / detached prototype — regardless of language. Allows disclosed dependency-seam substitution. "Fidelity, not language sameness" nuance + 3-question test + fake-vs-faithful example + rationalization table seeded from RED baselines.
• hooks/pretool-demo-fidelity-guard (advisory, NEVER blocks): demo-path nudge. Anchored heuristic (segment demos/examples or basename prefix demo*/example*/showcase*/quickstart*; excludes test/spec/testdata/fixtures/vendor segments + *_test.*/*.spec.*/*_spec.* basenames; lowercased). Session dedup on basename(transcript_path) (PreToolUse has no session_id); fails open (fires) on state I/O error; honors SUPERPOWERS_HOOKS_DISABLE=1.
• Wiring: RLV "Demonstration" change-class row (carves artifact-stub-forbidden vs disclosed-dependency-seam-allowed — no contradiction with "no stub on either end"); verification-before-completion demo/example works claim-matrix row; finishing Step 1b note; using-autodev cross-cutting listing; README + cross-llm-coverage rows.
• Version: 6.1.5 → 6.2.0 (all three manifests).

Runtime launch transcript (Step 1b — hooks.json = plugin-loading-path)

Launch: fires on demo path
$ printf '{"tool_name":"Write","tool_input":{"file_path":"examples/demo_main.go"},"cwd":"<repo>","transcript_path":"/tmp/t.jsonl"}' | bash hooks/pretool-demo-fidelity-guard
{"hookSpecificOutput":{"hookEventName":"PreToolUse","additionalContext":"<IMPORTANT>... See autodev:demonstration-fidelity ...</IMPORTANT>"}}

Launch: silent on normal path
$ printf '{"tool_name":"Write","tool_input":{"file_path":"internal/server.go"},...}' | bash hooks/pretool-demo-fidelity-guard
(no output — silent)

Failure-signature scrape: clean
Verdict: PASS

Test evidence

• tests/hook-contracts.sh: PASS (22 new demo-fidelity assertions — fires/silent/excluded incl. example_test.go/testdata//widget_spec.rb/.spec.ts/dedup/fail-open/disable-env/malformed-stdin/never-blocks)
• tests/skill-content-grep.sh: PASS (host-neutral)
• tests/skill-cross-refs.sh: PASS
• tests/version-check.sh: PASS (all manifests 6.2.0)
• tests/plan-scope-check.sh --plan --verify-lock: PASS (lock intact)
• GREEN behavioral test: subagent under fake-demo pressure WITH the skill ran the real handler, substituted only the Store dependency, and printed the disclosure — no hard-coding.

Review

• Design adversarial review: PASS (2 Criticals + 5 Importants resolved across cycles).
• Plan adversarial review: PASS (2 Criticals — incl. session_id→transcript_path — + 5 Importants resolved).
• Code review: PASS, zero Critical; Important I-1 (RSpec *_spec.rb) + Minors M-1/M-2 fixed in-PR.

Generated by the implementing agent (autodev pipeline dogfood).