feat: block vague-reference issue creation with content preflight (Closes #582)

Add a pre-create content gate to gitea_create_issue that fails closed with
BLOCKED + DIAGNOSE when the title/body is a vague reference to out-of-band
draft content ("the drafted issue", "the prepared issue", "the issue we
discussed", "the previous draft") and no durable source pointer (existing
issue/PR/comment, checked-in file, URL, or scratchpad path) is present.

- issue_content_gate.py: assess_issue_content / pre_create_issue_content_gate
  with vague-phrase detection, durable-source-pointer escape hatch, and a
  domination check so long specific bodies are not falsely blocked.
- gitea_create_issue: runs the gate after preflight purity, before duplicate
  search; new allow_incomplete_content override (off by default). Title-only
  creation stays allowed (no empty-body requirement) to preserve behavior.
- tests/test_issue_content_gate.py: unit + MCP integration coverage.
- create-issue.md: documents the enforced preflight with valid/invalid
  prompt examples.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

skills/llm-project-workflow/workflows/create-issue.md

@@ -344,6 +344,41 @@ If edits are needed, make the smallest correction necessary and report the corre
 
 Do not silently change requested meaning.
 
+## 14a. Enforced content preflight (#582)
+
+`gitea_create_issue` runs a **content preflight gate** before duplicate
+search or creation. It fails closed (returns `BLOCKED + DIAGNOSE`, no issue
+created) when the title/body is a *vague reference* to out-of-band draft
+content the session cannot prove it holds, and no durable source pointer is
+present.
+
+An LLM must never fabricate issue content from stale chat memory. If asked to
+create "the drafted issue" / "the prepared issue" / "the issue we discussed"
+/ "the previous draft" without the full content in the current context or a
+durable source pointer, stop and return `BLOCKED + DIAGNOSE` naming the exact
+vague/missing fields.
+
+A **durable source pointer** is one of: an existing issue/PR reference
+(`#582`), a comment id (`comment 8155`), a checked-in file path
+(`task_capability_map.py`), a URL, or a scratchpad path. When a pointer is
+present, retrieve the real content from it before creating.
+
+The gate does **not** require a non-empty body; explicit title-only creation
+stays allowed. It only blocks placeholder references. An operator may bypass
+it with `allow_incomplete_content=True` (report the override).
+
+**Invalid prompts (must block):**
+
+* "Create the drafted issue."
+* "File the prepared issue we discussed."
+* "Open the previous draft."
+
+**Valid prompts (proceed):**
+
+* Full title + body + acceptance criteria supplied inline.
+* "Create the issue drafted in `#582`." (durable pointer → fetch and use it)
+* "Create the issue from `scratchpad/issue-draft.md`." (durable file pointer)
+
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