feat: mount canonical gitea-workflow skill for Codex and MCP inventory (Closes #551)

Expose gitea-workflow / llm-project-workflow / git-pr-workflows as one
workflow router in mcp_list_project_skills, add preflight + Codex install
script, and document multi-runtime skill name parity.

docs/llm-workflow-runbooks.md

@@ -408,6 +408,25 @@ The guard blocks when the **control checkout** (repository root) is:
 `branches/...` directories are disposable role worktrees; the root checkout is
 the stable orchestration surface only.
 
+
+## Canonical workflow skill names (#551)
+
+Controller prompts and sessions must load the **same** workflow skill wall
+regardless of runtime (Claude, Codex, Gemini):
+
+| Name | Role |
+|------|------|
+| `gitea-workflow` | Primary controller / Codex skill name |
+| `llm-project-workflow` | Portable in-repo package |
+| `git-pr-workflows` | Legacy alias |
+
+- Inventory: `mcp_list_project_skills` lists all three.
+- Preflight: `mcp_check_workflow_skill_preflight` before mutations.
+- Codex install: `scripts/install-codex-workflow-skill.sh`
+- Full doc: [`docs/workflow-skill-mount.md`](workflow-skill-mount.md)
+
+If the skill is missing, stop with BLOCKED + DIAGNOSE — do not mutate.
+
 ## Shell Spawn Hard-Stop Rule
 
 Symptom: a shell tool call returns `exit_code: -1` with empty stdout/stderr.

docs/workflow-skill-mount.md

@@ -0,0 +1,68 @@
+# Workflow skill mount across runtimes (#551)
+
+## Problem
+
+Controller prompts require **`gitea-workflow`**, but:
+
+- Claude may load `~/.claude/skills/gitea-workflow`
+- Codex often has **no** `~/.codex/skills/gitea-workflow`
+- The portable package in-repo is `skills/llm-project-workflow`
+- `mcp_list_project_skills` historically listed operational guides only, not
+  the workflow router
+
+Sessions then either **block** incorrectly or **proceed without** the workflow
+wall.
+
+## Canonical names (must resolve to the same skill)
+
+| Name | Use |
+|------|-----|
+| `gitea-workflow` | **Primary** controller / Codex skill name |
+| `llm-project-workflow` | Portable in-repo package name |
+| `git-pr-workflows` | Legacy alias |
+
+Source of truth: `skills/llm-project-workflow/SKILL.md`  
+In-repo alias stub: `skills/gitea-workflow/SKILL.md`
+
+## Codex install
+
+From a `branches/` worktree (or any clone of the repo):
+
+```bash
+./scripts/install-codex-workflow-skill.sh
+# optional:
+./scripts/install-codex-workflow-skill.sh --dry-run
+./scripts/install-codex-workflow-skill.sh --skills-dir "$HOME/.codex/skills"
+```
+
+This symlinks the portable package under all three names. **Restart Codex**
+after install.
+
+## MCP discovery
+
+- `mcp_list_project_skills` includes `gitea-workflow`, `llm-project-workflow`,
+  and `git-pr-workflows`.
+- `mcp_get_skill_guide("<name>")` returns the same router steps for each.
+- `mcp_check_workflow_skill_preflight` proves the in-repo skill file exists and
+  reports Codex mount status.
+
+## Preflight rule
+
+Before any git or Gitea mutation:
+
+1. Call `mcp_check_workflow_skill_preflight`.
+2. If `blocked` / `workflow_skill_ready` is false → **BLOCKED + DIAGNOSE**; do
+   not mutate.
+3. Load the skill by **any** canonical name and follow the router.
+
+Missing Codex mount alone does not block if the in-repo skill is present and
+loaded via MCP/docs; operators should still install the Codex symlink so
+prompt names resolve natively.
+
+## Controller prompts
+
+Prefer:
+
+> Invoke skill `gitea-workflow` (alias of `llm-project-workflow`).
+
+Do not require a name that is only available on one runtime.