enh(#1243): consume Claude plugin-provided skills in agent_skills (epic #1258 Phase B) (#1261)

* feat(#1243): consume Claude plugin-provided skills via native Skill-tool directive + grant Skill to agent_skills-consumer agents

- Relax global skill name validation to accept namespaced form `^[A-Za-z0-9_-]+(:[A-Za-z0-9_-]+)*$`
- Namespaced names (containing colon) on claude runtime emit a Skill-tool load directive instead of a @-include line
- Namespaced names on non-claude runtimes are skipped with a warning
- Bare unresolved names retain existing warn-and-skip behavior (no promotion to directive)
- Grant `Skill` tool to all 22 agent_skills consumer agents; 5 generated agents updated via research-profiles.cjs + regen, 17 hand-authored agents edited directly
- Add 16 TDD tests in describe('bug #1243') covering happy/mixed/precedence/negative/cross-runtime/regression/grant cases

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs(#1243): document plugin-provided skills in agent_skills

Update the Agent Skills Injection reference in CONFIGURATION.md with
the three entry forms (project-relative, global:<name>,
global:<plugin>:<skill>), the Claude-only runtime behaviour of the
namespaced form and the warn-skip on other runtimes, the plugin
pre-install prerequisite, and the consumer-agent Skill tool grant.

Add docs/how-to/attach-a-plugin-skill-to-a-gsd-agent.md with a
step-by-step guide for installing the plugin, locating the namespaced
skill name, wiring it into agent_skills, and verifying injection.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(#1243): align agent_skills docs with emitted block format + mixed-block regression test (code-review)

- Replace two-section mixed-block example (bogus "Load these plugin-provided skills using the Skill tool:" header) with the actual single-section inline format in CONFIGURATION.md and docs/how-to/attach-a-plugin-skill-to-a-gsd-agent.md
- Fix quoted warning text in how-to doc to exactly match the emitted string: [agent-skills] WARNING: Plugin-namespaced skill "global:<name>" requires a Skill-tool-capable runtime (claude) — skipping on runtime "<runtime>"
- Replace phantom agent slugs (gsd-checker, gsd-researcher, gsd-advisor, gsd-synthesizer) in CONFIGURATION.md Supported Agent Types with real agents/gsd-*.md examples (gsd-plan-checker, gsd-phase-researcher, gsd-code-reviewer, gsd-ui-auditor, gsd-research-synthesizer)
- Add byte-identical mixed-block regression test: one path-resolvable global skill + one plugin-namespaced skill on claude runtime → asserts r.ir.block === single-section interleaved block, no secondary header

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(#1243): regenerate agent-size baseline for the Skill-tool grant

The 22 agent_skills-consumer agents each grew +7 bytes from adding `Skill`
to their tools list; refresh the committed per-agent size baseline (#1074 guard).

* chore(#1243): add Added changeset fragment

* fix(#1243): traceable allow-test-rule ref + separator-agnostic byte-identical tests (CI)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

agents/gsd-advisor-researcher.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-advisor-researcher
 description: Researches a single gray area decision and returns a structured comparison table with rationale. Spawned by discuss-phase advisor mode.
-tools: Read, Bash, Grep, Glob, WebSearch, WebFetch, mcp__context7__*
+tools: Read, Bash, Grep, Glob, Skill, WebSearch, WebFetch, mcp__context7__*
 color: cyan
 ---
 

agents/gsd-assumptions-analyzer.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-assumptions-analyzer
 description: Deeply analyzes codebase for a phase and returns structured assumptions with evidence. Spawned by discuss-phase assumptions mode.
-tools: Read, Bash, Grep, Glob
+tools: Read, Bash, Grep, Glob, Skill
 color: cyan
 ---
 

agents/gsd-code-fixer.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-code-fixer
 description: Applies fixes to code review findings from REVIEW.md. Reads source files, applies intelligent fixes, and commits each fix atomically. Spawned by /gsd:code-review --fix.
-tools: Read, Edit, Write, Bash, Grep, Glob
+tools: Read, Edit, Write, Bash, Grep, Glob, Skill
 color: green
 # hooks:
 #   - before_write

agents/gsd-code-reviewer.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-code-reviewer
 description: Reviews source files for bugs, security issues, and code quality problems. Produces structured REVIEW.md with severity-classified findings. Spawned by /gsd:code-review.
-tools: Read, Write, Bash, Grep, Glob
+tools: Read, Write, Bash, Grep, Glob, Skill
 color: orange
 # hooks:
 #   - before_write

agents/gsd-codebase-mapper.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-codebase-mapper
 description: Explores codebase and writes structured analysis documents. Spawned by map-codebase with a focus area (tech, arch, quality, concerns). Writes documents directly to reduce orchestrator context load.
-tools: Read, Bash, Grep, Glob, Write
+tools: Read, Bash, Grep, Glob, Write, Skill
 color: cyan
 # hooks:
 #   PostToolUse:

agents/gsd-debugger.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-debugger
 description: Investigates bugs using scientific method, manages debug sessions, handles checkpoints. Spawned by /gsd:debug orchestrator.
-tools: Read, Write, Edit, Bash, Grep, Glob, WebSearch
+tools: Read, Write, Edit, Bash, Grep, Glob, Skill, WebSearch
 color: orange
 # hooks:
 #   PostToolUse:

agents/gsd-doc-writer.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-doc-writer
 description: Writes and updates project documentation. Spawned with a doc_assignment block specifying doc type, mode (create/update/supplement), and project context.
-tools: Read, Bash, Grep, Glob, Write, Edit
+tools: Read, Bash, Grep, Glob, Write, Edit, Skill
 color: purple
 # hooks:
 #   PostToolUse:

agents/gsd-eval-auditor.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-eval-auditor
 description: Retroactive audit of an implemented AI phase's evaluation coverage. Checks implementation against the AI-SPEC.md evaluation plan. Scores each eval dimension as COVERED/PARTIAL/MISSING. Produces a scored EVAL-REVIEW.md with findings, gaps, and remediation guidance. Spawned by /gsd:eval-review orchestrator.
-tools: Read, Write, Bash, Grep, Glob
+tools: Read, Write, Bash, Grep, Glob, Skill
 color: red
 # hooks:
 #   PostToolUse:

agents/gsd-executor.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-executor
 description: Executes GSD plans with atomic commits, deviation handling, checkpoint protocols, and state management. Spawned by execute-phase orchestrator or execute-plan command.
-tools: Read, Write, Edit, Bash, Grep, Glob, mcp__context7__*
+tools: Read, Write, Edit, Bash, Grep, Glob, Skill, mcp__context7__*
 color: yellow
 # hooks:
 #   PostToolUse:

agents/gsd-integration-checker.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-integration-checker
 description: Verifies cross-phase integration and E2E flows. Checks that phases connect properly and user workflows complete end-to-end.
-tools: Read, Bash, Grep, Glob
+tools: Read, Bash, Grep, Glob, Skill
 color: blue
 ---
 

agents/gsd-nyquist-auditor.md

@@ -8,6 +8,7 @@ tools:
   - Bash
   - Glob
   - Grep
+  - Skill
 color: purple
 ---
 

agents/gsd-phase-researcher.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-phase-researcher
 description: Researches how to implement a phase before planning. Produces RESEARCH.md consumed by gsd-planner. Spawned by /gsd:plan-phase orchestrator.
-tools: Read, Write, Edit, Bash, Grep, Glob, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
+tools: Read, Write, Edit, Bash, Grep, Glob, Skill, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
 color: cyan
 # hooks:
 #   PostToolUse:

agents/gsd-plan-checker.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-plan-checker
 description: Verifies plans will achieve phase goal before execution. Goal-backward analysis of plan quality. Spawned by /gsd:plan-phase orchestrator.
-tools: Read, Bash, Glob, Grep
+tools: Read, Bash, Glob, Grep, Skill
 color: green
 ---
 

agents/gsd-planner.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-planner
 description: Creates executable phase plans with task breakdown, dependency analysis, and goal-backward verification. Spawned by /gsd:plan-phase orchestrator.
-tools: Read, Write, Edit, Bash, Glob, Grep, WebFetch, mcp__context7__*
+tools: Read, Write, Edit, Bash, Glob, Grep, Skill, WebFetch, mcp__context7__*
 color: green
 # hooks:
 #   PostToolUse:

agents/gsd-project-researcher.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-project-researcher
 description: Researches domain ecosystem before roadmap creation. Produces files in .planning/research/ consumed during roadmap creation. Spawned by /gsd:new-project or /gsd:new-milestone orchestrators.
-tools: Read, Write, Bash, Grep, Glob, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
+tools: Read, Write, Bash, Grep, Glob, Skill, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
 color: cyan
 # hooks:
 #   PostToolUse:

agents/gsd-research-synthesizer.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-research-synthesizer
 description: Synthesizes research outputs from parallel researcher agents into SUMMARY.md. Spawned by /gsd:new-project after 4 researcher agents complete.
-tools: Read, Write, Bash
+tools: Read, Write, Bash, Skill
 color: purple
 # hooks:
 #   PostToolUse:

agents/gsd-roadmapper.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-roadmapper
 description: Creates project roadmaps with phase breakdown, requirement mapping, success criteria derivation, and coverage validation. Spawned by /gsd:new-project orchestrator.
-tools: Read, Write, Bash, Glob, Grep
+tools: Read, Write, Bash, Glob, Grep, Skill
 color: purple
 # hooks:
 #   PostToolUse:

agents/gsd-security-auditor.md

@@ -8,6 +8,7 @@ tools:
   - Bash
   - Glob
   - Grep
+  - Skill
 color: red
 ---
 

agents/gsd-ui-auditor.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-ui-auditor
 description: Retroactive 6-pillar visual audit of implemented frontend code. Produces scored UI-REVIEW.md. Spawned by /gsd:ui-review orchestrator.
-tools: Read, Write, Bash, Grep, Glob
+tools: Read, Write, Bash, Grep, Glob, Skill
 color: pink
 # hooks:
 #   PostToolUse:

agents/gsd-ui-checker.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-ui-checker
 description: Validates UI-SPEC.md design contracts against 6 quality dimensions. Produces BLOCK/FLAG/PASS verdicts. Spawned by /gsd:ui-phase orchestrator.
-tools: Read, Bash, Glob, Grep
+tools: Read, Bash, Glob, Grep, Skill
 color: cyan
 ---
 

agents/gsd-ui-researcher.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-ui-researcher
 description: Produces UI-SPEC.md design contract for frontend phases. Reads upstream artifacts, detects design system state, asks only unanswered questions. Spawned by /gsd:ui-phase orchestrator.
-tools: Read, Write, Edit, Bash, Grep, Glob, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
+tools: Read, Write, Edit, Bash, Grep, Glob, Skill, WebSearch, WebFetch, mcp__context7__*, mcp__firecrawl__*, mcp__exa__*, mcp__tavily__*, mcp__ref__*, mcp__jina__*
 color: purple
 # hooks:
 #   PostToolUse:

agents/gsd-verifier.md

@@ -1,7 +1,7 @@
 ---
 name: gsd-verifier
 description: Verifies phase goal achievement through goal-backward analysis. Checks codebase delivers what phase promised, not just that tasks completed. Creates VERIFICATION.md report.
-tools: Read, Write, Bash, Grep, Glob
+tools: Read, Write, Bash, Grep, Glob, Skill
 color: green
 # hooks:
 #   PostToolUse: