claude-handoff: add to in-progress README index

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

skills/in-progress/README.md

@@ -8,3 +8,4 @@ Skills that are still being developed. They're not ready to ship — expect roug
 - **[writing-beats](./writing-beats/SKILL.md)** — Shape an article as a journey of beats, choose-your-own-adventure style. Pick a starting beat, write only that beat, then pivot to the next, until the article reaches a natural end.
 - **[writing-fragments](./writing-fragments/SKILL.md)** — Grilling session that mines you for fragments — heterogeneous nuggets of writing — and appends them to a single document as raw material for a future article.
 - **[writing-shape](./writing-shape/SKILL.md)** — Take a markdown file of raw material and shape it into an article paragraph by paragraph, arguing format choices at each step.
+- **[claude-handoff](./claude-handoff/SKILL.md)** — Hand the current conversation off to a fresh background agent that picks up the work immediately, seeded with a handoff summary via `claude --bg`. User-invoked.

skills/in-progress/claude-handoff/SKILL.md

@@ -0,0 +1,18 @@
+---
+name: claude-handoff
+description: Hand the current conversation off to a fresh background agent that picks up the work immediately.
+argument-hint: "What will the next session be used for?"
+disable-model-invocation: true
+---
+
+Write a handoff summary of the current conversation so a fresh agent can continue the work. Instead of saving it, launch a background agent seeded with the summary as its prompt: `claude --bg --name "<descriptive name>" "<handoff summary>"`. It starts in the current working directory and returns immediately; the user manages it with `claude agents`.
+
+Always pass `-n`/`--name` with a descriptive name (e.g. `--name "Fix login bug"`) — it sets the display name shown in the job list, session picker, and terminal title.
+
+Include a "suggested skills" section in the summary, which suggests skills that the agent should invoke.
+
+Do not duplicate content already captured in other artifacts (PRDs, plans, ADRs, issues, commits, diffs). Reference them by path or URL instead.
+
+Redact any sensitive information, such as API keys, passwords, or personally identifiable information — the summary becomes the agent's prompt.
+
+If the user passed arguments, treat them as a description of what the next session will focus on and tailor the summary accordingly.