feat(session-flow)!: move retro trends to /session-flow:audit-sessions trends #12123

Parent #7575 decides "Retro trends moves to /session-flow:audit-sessions, the all-transcripts source for codify (D50 item 3, D53)", and names this as half of the retro-absorb-and-trends-move slice, which was never filed. The owner approved D53 on 2026-10-13 (poteto-review decision row 53): "move retro trends to audit-sessions". D50 item 3, approved the same day, reads "audit-sessions stays the all-transcripts-on-this-machine source, retro stays one chain". On main, trends is still a retro mode (plugins/session-flow/skills/retro/SKILL.md:2,3,12,70,114,166, context/trends.md), and audit-sessions says its sweep measures "no trend over time" (plugins/session-flow/skills/audit-sessions/SKILL.md, Purpose). The score history both skills use is this plugin's state file ${CLAUDE_PLUGIN_DATA}/scores/<project-slug>.md, which retro session and quick modes keep writing. This is a cut to /session-flow:retro, so a host session does it: the PR's Verification section carries before/after evals (retro's remaining cases, the moved trends cases, the trigger probes for probes/retro.json and probes/audit-sessions.json, run concurrently with the same flags) and a /docs-hygiene:compress compare over retro's SKILL.md, in the shape of PR #9328.

Done when

• plugins/session-flow/skills/retro/context/trends.md no longer exists. Its process, including the step 6 delivery metrics through /work-items:measure-delivery, lives in a file under plugins/session-flow/skills/audit-sessions/.
• That file, or audit-sessions SKILL.md "Paths", states the score history path ${CLAUDE_PLUGIN_DATA}/scores/<project-slug>.md and how <project-slug> is derived (the same rule as retro SKILL.md "Paths"). It does not point into retro's files for either.
• plugins/session-flow/skills/audit-sessions/SKILL.md adds trends throughout:
  • in the argument-hint, the Arguments line and its full form;
  • in the action count and the accepted set that "Stop and name this accepted set" checks;
  • in a section for the action that reads the moved file and states which options trends takes.
• The audit-sessions Purpose no longer says the skill measures no trend over time without naming trends, and its description gains a trigger for score trends ("show trends" or "how am I doing").
• plugins/session-flow/skills/retro/SKILL.md no longer offers trends:
  • it is gone from the description, argument-hint, the Arguments line, the Step 0 mode table, the Step 2 handoff table and the /insights Routing sentence;
  • /session-flow:retro trends stops and names /session-flow:audit-sessions trends;
  • retro's ## Next names /session-flow:audit-sessions trends for cross-session score history.
• The trends mention in plugins/session-flow/skills/retro/reference/native-insights.md (:18 on main) names /session-flow:audit-sessions trends.
• Evals move with the mode:
  • the three cases trends-mode-routing, trends-reads-delivery-metrics-when-available and trends-names-missing-measure-delivery leave plugins/session-flow/skills/retro/evals/evals.json and are added to plugins/session-flow/skills/audit-sessions/evals/evals.json, with prompts that invoke /session-flow:audit-sessions trends;
  • retro's remaining cases no longer list trends among its modes;
  • retro gains a case in which /session-flow:retro trends names /session-flow:audit-sessions trends and analyzes no session.
• Trigger probes follow:
  • in plugins/session-flow/probes/retro.json, pos-train-05 ("Show me trends across my last several retros.") becomes a negative with the next free neg-train- id, and ranking_note says why;
  • plugins/session-flow/probes/audit-sessions.json gains that request as a positive.
• plugins/session-flow/README.md lists the command as /session-flow:audit-sessions trends and not as /session-flow:retro trends (:225,233 on main).
• plugins/session-flow/skills/workflow/context/steps.md step 12 (:189 on main) no longer credits retro with trend tracking, or names /session-flow:audit-sessions trends for it.
• Every line of plugins/session-flow/skills/retro/SKILL.md that git grep -n -w trends prints also contains audit-sessions trends.
• git grep -n -E '/(session-flow:)?retro trends' -- plugins docs ':!**/CHANGELOG.md' ':!.changes/**' ':!plugins/session-flow/skills/retro/SKILL.md' ':!plugins/session-flow/skills/retro/evals/evals.json' prints nothing. The frozen probe neg-train-02 in probes/running-retro.json ("Show retro trends over the past month.") stays unchanged.
• A .changes/session-flow/*.md fragment with bump: major describes the move: /session-flow:retro trends stops working, as the show-options rename in feat(session-flow)!: rename show-options to recommend-skills #11149 did with its old command.
• The PR's Verification section shows the before/after eval results and the compress-compare verdict, with no case lost.
• The PR's CI is green.

Out of scope

• Matt's retro findings (slice S1).
• Moving codify or the audit-sessions style pass (D50 item 3 and the corrections plugin).
• Changing what the score history records or the five scored dimensions.

Parent: #7575