feat(linkedin-studio): N13 — publiserings-slots + vacancy-varsel + WIP-roll-up + slot-default [skip-docs]

A1-10 + D-5. The queue answers "what is scheduled"; nothing answered "is the week
covered, and what is still being written". N13 makes both readable at session start.

- Publishing slots are operator config: profile/publishing-slots.json in the per-user
  data dir, schema + OPT-IN template in config/publishing-slots.template.json. The
  plugin ships no publishing times and writes the grid for nobody; absent config means
  every slot surface stays silent (same never-nag discipline as the trend/brain nudges).
  Data dir rather than the state file, which is machine-written and whose frontmatter
  reader does not parse lists.
- hooks/scripts/slots.mjs (new): one implementation behind four surfaces. Zero-dep (a
  SessionStart hook must not spawn tsx), pure core (dates in as strings, no clock),
  imported by the commands exactly as queue-manager.mjs already is — so session-start's
  vacancy warning and Step 10's slot default cannot drift apart.
- Coverage counts the short-form queue (scheduled/published; cancelled frees the slot)
  AND editions-register rows claiming that date, counted per date, so long-form and
  short-form cannot be double-booked and a two-slot day needs two posts.
- Session start gains "## Editions in Flight" (series, phase, next action, claimed slot,
  days in flight) and "## Publishing Slots" (next open slot, open count in 14 days, and
  how to fill it when the gap is <=3 days). The existing discovery nudge is untouched.
- /linkedin router + /linkedin:calendar surface the same roll-up; calendar documents the
  opt-in copy. /linkedin:newsletter Step 10 defaults to the next open slot (one
  confirmation, not an interview) and writes --slot onto the register row.
- D-5: references/scheduling-strategy.md marked "confidence: low / directional" per the
  algorithm reference's own standard, deferring to the operator's grid and their own
  analytics. Neutral example time replaces the operator-specific one in the N12 docs.

TDD: red proven first (module absent; 5 session-start behaviours failing).
hooks 140 -> 174 · test-runner 184 -> 197 (Section 16t: 13 unconditional greps incl. a
de-niche check that no publishing time is hardcoded in the slot path and no operator grid
is committed, + non-vacuity self-test; anti-erosion floor 166 -> 179).
Suites green: trends 300/0 · brain 134/0 · editions 72/0 · specifics-bank 45/0 ·
tests 35/0 · render 60/0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QxvWAjte7vPcF79QeSRvRJ

references/scheduling-strategy.md

@@ -1,10 +1,27 @@
 # Post Scheduling Strategy
 
-Reference for calculating optimal posting schedule based on weekly goal and content mix.
+Reference for calculating a posting schedule from weekly goal and content mix.
 
-## Optimal Posting Slots
+## Epistemic status (D-5)
 
-Based on `weekly_goal` from state file:
+**Confidence: low / directional** for every day/time in this file — practitioner
+heuristic, no primary source. Same standard as
+`references/algorithm-signals-reference.md`: treat these as a hypothesis to test per
+account, not as a finding about your audience. LinkedIn publishes no optimal-time data,
+and the numbers below come from general B2B practitioner lore, not from measurement of
+*your* followers.
+
+The authoritative grid is therefore the **operator's own**, in
+`${LINKEDIN_STUDIO_DATA:-$HOME/.claude/linkedin-studio}/profile/publishing-slots.json`
+(schema + opt-in: `config/publishing-slots.template.json`). That file is what
+`/linkedin:calendar`, the session-start vacancy warning and `/linkedin:newsletter`
+Step 10 actually read. The tables here are the **starting point** it is seeded from,
+to be replaced with what `/linkedin:report` and `/linkedin:analyze` show for the
+account — the plugin hardcodes no publishing times.
+
+## Directional Posting Slots
+
+Based on `weekly_goal` from state file (times: low / directional — test per account):
 
 ### 2x/week
 | Slot | Day | Time (CET) | Rationale |
@@ -38,9 +55,14 @@ Based on `weekly_goal` from state file:
 
 ## Scheduling Algorithm
 
+When the operator has a configured grid, `hooks/scripts/slots.mjs` answers "what is the
+next free slot" deterministically (`nextFreeSlot`) — coverage counts both queue entries
+and editions-register rows, so long-form and short-form cannot be scheduled on top of
+each other. The steps below are the fallback for an unconfigured grid.
+
 When assigning dates to batch-created posts:
 
-1. **Start from next available optimal slot** after today
+1. **Start from next available slot** after today
 2. **Skip slots that already have queued posts** (check queue.json)
 3. **If all slots this week are taken**, spill into next week
 4. **Assign in slot order** (earliest available first)
@@ -77,6 +99,11 @@ Ensure coverage across expertise areas:
 
 ## Time Zone Notes
 
+Also low / directional, and written from one European vantage point — read the peaks
+below as an illustration of the *shape* of the question, not as your audience's hours.
+The operator's grid records its own IANA zone; the plugin schedules in local wall-clock
+time and converts nothing.
+
 - All times are CET (Central European Time)
 - Norwegian audience peaks: 7:30-9:00 and 11:30-13:00
 - For international audiences, 08:30 CET catches both EU morning and US east coast pre-work