idle-draft: idle-subscription dispatcher for the writing pipeline

Elapsed-paced gates, bounded-parallel event-driven dispatch, filesystem-
derived stages with thin human-gate state, citation validation with
quarantine, credential parity check, prompt templates as data.
Per IDLE-DRAFT-PLAN.md in writing/oreillyconsulting.

Claude-Session: https://claude.ai/code/session_01YQDoWNM7XPPii28khFWoMc

data/idle-draft/prompts/topic-ideas.md

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+You are proposing **new candidate topics** for one dossier in the O'Reilly Consulting
+writing pipeline. This runs only when no other work is currently eligible — the
+dossier's existing topics are all blocked on a human step or already have enough work
+in flight. Do not invent structure; follow this brief.
+
+## Dossier
+
+- Dossier: `$dossier`
+- Dossier commissioning guide: $dossier_agents_path
+- Project-root voice and citation rules: $agents_root_path
+- Voice reference: $style_dir/goes-target-voice.md
+
+Evidence you may cite must live under one of these directories (you have read access
+via `--add-dir`):
+
+$evidence_dirs
+
+## Do not duplicate an existing topic
+
+These titles already exist as numbered topic briefs or open proposals in this dossier.
+Do **not** propose anything that duplicates or trivially rephrases one of these:
+
+$existing_titles
+
+## What to produce
+
+Propose **up to $max_new** new candidate topics for this dossier, each grounded in
+something you actually found under the evidence directories above — not a generic
+industry-trend guess. For each candidate:
+
+- A working title (sentence case, matching the dossier's existing topic-title style).
+- A one-paragraph pitch: the decision or toil the topic would address, matching the
+  audience of this dossier (CTO/VP for consulting dossiers, implementing engineers for
+  technical dossiers — see `$dossier_agents_path` for which this is).
+- 2–4 evidence pointers: file paths under the evidence directories, with a one-line
+  note on what each contains. Use the dossier's correct status-label family (see
+  `$agents_root_path`) on each.
+
+You are proposing, not commissioning: **never create a numbered `NN-slug` file.** A
+human promotes a proposal to a numbered brief later.
+
+## Required structure (append this, do not replace the file)
+
+```markdown
+## <Working title, sentence case>
+
+**Pitch:** <one paragraph>
+
+**Evidence:**
+
+- <path> — <one-line note, status label>
+- <path> — <one-line note, status label>
+```
+
+One `##` block per proposed topic. All headings sentence case. No vendor names in
+prose for consulting dossiers (`ai`, `devops-2020`) — vendor names may stay in the
+evidence pointers' one-line notes only.
+
+## Output
+
+Write **only the new `##` blocks** (not the whole file — this content will be appended
+to the dossier's existing `TOPIC-PROPOSALS.md`) to exactly this path:
+
+    $output_path
+
+The dispatcher validates this file (non-empty, starts with a top-level `##` heading)
+and appends it to the canonical proposals file itself.