Capture drafting-quality feedback: feed post-merge gaps back into #8103's issue-drafting tool

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Problem

The maintainer named the actual current bottleneck in scoping #8103: "if my issues aren't extremely explicit, I usually end up finding more gaps/problems after merging their work." #8103 cuts the time cost of writing an explicit issue, but has no way to get BETTER at it over time — every draft is independent, with no memory of past misses. This issue closes that loop.

Area

Extends #8103's core module — not a separate tool.

Proposal

• When the maintainer finds a real post-merge gap traceable to an issue's draft (something the draft should have specified but didn't — the exact failure mode tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103 exists to prevent), record it as a concrete "drafting miss": the loose prompt that was given, the draft that was produced, and what was actually missing.
• Feed the accumulated set of misses back into tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103's grounding process — at minimum, as a growing checklist of gap categories to double-check for on every future draft (e.g. "did I verify this exact function still has this exact signature," "did I state the anti-pattern explicitly," mirroring the concrete lessons already written into .claude/skills/contributor-pipeline-gardening/reference.md's own "what broke once already" sections). A more capable version could use the misses as few-shot examples in the drafting prompt itself — leave the exact mechanism to whoever builds this, informed by how tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103 actually turns out.
• Recording a miss must be cheap and manual (the maintainer flags it after the fact) — this issue does not need to auto-detect gaps itself, only to capture them once found and make the tool learn from them.

Deliverables

• A way to record a drafting miss (a file, a small log, whatever fits tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103's own storage — no new database).
• tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103's core module reads and applies the accumulated misses on every subsequent draft.

Resources

• Epic: verifiable pre-merge backtest for ORB/AMS deterministic rules #8082 (parent epic), tooling: maintainer CLI to expand a loose issue prompt into a gate-ready contributor issue #8103 (the tool this extends)
• .claude/skills/contributor-pipeline-gardening/reference.md (the existing style of "concrete lesson from a real incident" this should follow — see its "gate only enforces explicit text" and "reuse-existing-pattern" sections for the exact tone)

Boundaries

Cannot be built before #8103 exists. Does not attempt to auto-detect gaps from a merged PR — a human still decides what counts as a real miss.

maintainer-only — internal tooling quality loop, not a build task for contributors.

[linear-code]

JSO-5599