chore(memory): BDR-081 + LRN-139 + journal + CHANGELOG + plan (opus5 tuning)

Capitalizes the Claude-5-family config recalibration: decision record,
trait-inversion learning (LRN-030 superseded premise, #80988 injections,
no-effort-hold trap), journal line, CHANGELOG Unreleased entries, and the
challenged plan (3 blind Opus 5 lenses, synthesis in §5bis).

.claude/memory/learnings.md

@@ -1355,3 +1355,9 @@ rules:
 - **context**: user asked to gitignore transient planning artifacts (`docs/superpowers/{specs,plans}`, `.claude/tasks/{contracts,plans}`) to stop them merging. BDR-065 had already REJECTED gitignore for docs/superpowers on the git-travel ground; the real gap was the DELETE side never being coded (doctrine-only manual chore, slipped once — 655e364). Built `_gitflow_purge_transient`.
 - **future application**: "don't merge transient X" → ask: does the run read X from disk? does X travel via git (worktree, foreign checkout)? Yes → auto-purge at finish, not gitignore. Scoped commit `-- <paths>` avoids sweeping a dirty index; `git diff --quiet HEAD -- paths` precheck makes `git rm` all-or-nothing safe; keep the purge best-effort so cleanup NEVER blocks a merge. Prove archive-reachability with `git log --full-history` / `git show <sha>:path` — plain `git log -- path` prunes the purged add-commit via history simplification (bit me writing T17).
 - **link**: [[BDR-065]].
+
+## LRN-139 — model-trait compensations invert across generations; state WHEN-guidance, not direction (2026-07-30)
+- **pattern**: config rules that COMPENSATE a model trait become counter-productive when the next generation inverts the trait. LRN-030 (Opus 4.8 under-delegates → "Default to delegation… counters under-delegation") inverted by Opus 5 (delegates MORE readily, official guide) — the rule pushed the failure the model now has. Same class: explicit verify instructions → over-verification; conservative-reporting clauses → literal recall suppression; MUST/CRITICAL → over-triggering.
+- **Opus 5 traps found**: (a) Claude Code injects Opus-5-only anti-delegation prompt sections (heron_brook + subagent_steer_delegation, issue #80988; server-gated, no opt-out, absent from transcripts) — own prose stacks on top blindly; (b) NO model-default effort hold on Opus 5 — persisted effortLevel (xhigh, settings.json) silently carries over, against "start high, sweep low/medium"; run /effort sweep per model; (c) effort does NOT shorten visible output/deliverables — only prose length rules do (+30-40% docs).
+- **future application**: at every model-generation bump, grep config for trait-compensating language ("counters model tendency…", "default to X") and re-verify the premise; prefer WHEN-guidance (conditions where X pays) over directional nudges — survives inversions unchanged.
+- **link**: [[LRN-030]] [[BDR-081]].