fix(story-mode): slash commands, and where a compaction belongs

A local slash command (`/compact`, `/model`) gets no reply from Claude and no
turn_duration, so its turn stayed "Claude is working" until the next prompt.
It now ends at the command's own output (<local-command-stdout>, kept for
the mission drawer) and reads "You run /compact.". `/compact` writes its
compaction marker before the command line itself; a marker that lands
between turns now belongs to the turn after it (it was drawn at the end of
the previous, finished turn), and one mid-turn stays where it is.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/api-reference.md

@@ -1067,7 +1067,7 @@ Responses carry a weak `ETag` with `Cache-Control: no-cache`; a request with a m
 
 A `page` carries the turn's summary fields plus `events` (one per prompt, sentence Claude wrote and tool call, with `intent`, `ok` when the call returned, `edit` hunks in Claude Code's own `structuredPatch` shape, the tail of `output`, `helper`, `tests` counts, and `files` for the files a Bash call printed with `cat`/`head`/`tail`, as the command named them), `panels` (each `{ kind, events, caption: { story, director }, balloon?, files?, ... }`, at most 12 per page, indices into `events`), `filesChanged`, `added`, `removed`, `helpers`, `helpersRunning`, `partial` (the turn began before the part that was read) and `truncated` (older outputs were dropped to keep the page small). A transcript that cannot be read is a `500` with `OPERATION_FAILED`.
 
-A helper started in the background (`helper.background`) carries `helper.running: true` until its `<task-notification>` arrives; that notification starts a turn of its own (origin `task`), whose prompt event carries the helper's answer as `output`, and the answer, tool count and duration are joined back onto the helper in the turn that started it. Claude Code times such a turn from the prompt that started the chain; Story Mode caps a turn's `durationMs` at the turn's own span. A helper started as a teammate (`status: teammate_spawned`) is a background helper too, and its `<teammate-message>` reports join it by name. A prompt that arrives while Claude works (typed, a background job's report, a message from another session) is written by current Claude Code builds as a `queued_command` attachment, not a user line; it joins the running turn, a prompt event carrying `origin` (`human`, `task`, `peer`, `system`), and a report that lands mid-turn is an event with intent `notice` rather than a new mission panel. A Bash call that writes files through here-documents (`cat > f <<'EOF'`) carries them as `edits` (whole-file edits, counted in `filesChanged`), and its label leaves the bodies out; `headline` is the part of a one-liner that decided its intent. The advisor (a server tool) is an event with tool `Advisor` and intent `helper`; its answer is encrypted in the transcript. `tests` may carry `errors` (pytest's collection errors). A turn ends at `turn_duration`, or at the Stop hook's `stop_hook_summary` (unless it prevented the stop) in sessions that never write `turn_duration`, timed then by its own span.
+A helper started in the background (`helper.background`) carries `helper.running: true` until its `<task-notification>` arrives; that notification starts a turn of its own (origin `task`), whose prompt event carries the helper's answer as `output`, and the answer, tool count and duration are joined back onto the helper in the turn that started it. Claude Code times such a turn from the prompt that started the chain; Story Mode caps a turn's `durationMs` at the turn's own span. A helper started as a teammate (`status: teammate_spawned`) is a background helper too, and its `<teammate-message>` reports join it by name. A prompt that arrives while Claude works (typed, a background job's report, a message from another session) is written by current Claude Code builds as a `queued_command` attachment, not a user line; it joins the running turn, a prompt event carrying `origin` (`human`, `task`, `peer`, `system`), and a report that lands mid-turn is an event with intent `notice` rather than a new mission panel. A Bash call that writes files through here-documents (`cat > f <<'EOF'`) carries them as `edits` (whole-file edits, counted in `filesChanged`), and its label leaves the bodies out; `headline` is the part of a one-liner that decided its intent. The advisor (a server tool) is an event with tool `Advisor` and intent `helper`; its answer is encrypted in the transcript. `tests` may carry `errors` (pytest's collection errors). A slash command is a prompt event with tool `Command`; a local one (`/compact`, `/model`) ends its turn at its own output (`<local-command-stdout>`, kept as the event's `output`), and a compaction that lands between turns belongs to the turn after it. A turn ends at `turn_duration`, or at the Stop hook's `stop_hook_summary` (unless it prevented the stop) in sessions that never write `turn_duration`, timed then by its own span.
 
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