artifact-path

# Artifact Path `.lets/` is ONE directory shared by every worktree of the repo (whole-dir symlink). Two sessions writing the same artifact kind on the same day used to overwrite each other (lets-05c4s - a plan review was lost). This skill is the single place that names an artifact and guarantees the path is free. **Contract:** args `kind=<kind> ext=<md|json> [task=<task-id>]`. Output: ONE echoed line `ARTIFACT_FILE=<absolute path>`. The caller writes to that path VERBATIM - never recomputes the stamp, never strips the `-vN` suffix, never writes anywhere else. ## Name shape `{YYYY-MM-DD}-{HHMM}-{ID}-{KIND}[-vN].{EXT}` under the kind's directory: | kind | directory | |------|-----------| | `plan` | `.lets/plans/` | | `review-local`, `review-branch`, `review-pr-<n>`, `review-plan` | `.lets/reviews/` | | `snapshot`, `snapshot-precompact` | `.lets/sessions/` | `ID` is the task id when one is active (MANDATORY whenever a task exists - same rule as `feature/<task-id>-...` branches). With no task: `{branch-slug}-{6hex}`, 6hex = first 6 chars of `$CLAUDE_CODE_SESSION_ID`, so two taskless sessions on `main` still get distinct names. `-vN` (v2, v3, ...) is appended whenever the path already exists - for task and taskless alike. ## Step 1: Resolve the task id If the caller passed `task=`, use it. Otherwise invoke `Skill(skill: "lets:detect-task", args: "fallback=no")` and use its result (may be empty). `fallback=no` is mandatory: the searched fallback asks a question, and a taskl...