drift-session-handover-authoringlisted

# Drift Session Handover Authoring Use this skill when you are about to call `drift_session_end` and must produce the handover artifacts required by ADR-079 and the session-handover contract in `.github/prompts/_partials/session-handover-contract.md`. ## When To Use - You touched files under `src/drift/` during the session. - You completed one or more fix-plan tasks. - You ran multiple scans / diffs / nudges and want to hand off to the next agent (or to the maintainer). - `drift_session_end` returned `DRIFT-6100` and you need to fill the missing artifacts. ## When Not To Use - Empty sessions (no tool calls beyond session start, no completed tasks, no touched files). The gate auto-exempts them. - Pure read-only exploration that touched no code. ## Core Rules 1. **Agent writes, server validates.** You author the artifacts. The MCP server only checks existence, shape, placeholders (and optionally runs an LLM review). Do not try to satisfy the gate with generated filler. 2. **No placeholder tokens.** `TODO`, `FIXME`, `XXX`, `TBD`, `???`, `<N>`, `<NNN>`, `LOREM`, `IPSUM`, `FOO`, `BAR`, `BAZ` outside of ≥5-line code fences block the gate at L3. 3. **Cross-check session id.** The `session_id` in the Markdown frontmatter must match the active session exactly. 4. **SIGNAL / ARCHITECTURE classes require all three artifacts.** Evidence JSON, ADR draft, and session markdown. 5. **`force=true` is a last resort.** It requires an auditable `bypass_reason` o