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Trim 2026-05 cycle — methodology + outcomes

Status: Phases 1, 2, 4 + In-context Retrieval Upgrade SHIPPED to trim-experiment branch on 31 May 2026 (NZST). Phase 3 (rule-card refactor) DEFERRED for Sush approval. Final merge to main pending burn-in (3-5 days).

Session: 71f7012b-2ab0-4d2a-a32c-107afe562816 · model: Claude Opus 4.7 (1M context).

🔴 Durability goal NOT FULLY achieved this cycle. Rule #9 (Portal-First Retrieval) is the structural fix the cycle delivered, but its enforcement vector (Phase 3 — rule cards with provenance pointers) was deferred. This is honestly labelled here so future-Atlas doesn't claim victory prematurely.

1. Why this cycle existed

After the 30 May 2026 brain-sync v3 PIVOT (one-repo private mirror at susanthgit/atlas-brain, commit 1cb85eb), the live brain (~/.copilot/*.md) was pristine and SHA256-verified against the mirror baseline for the first time ever. Trim could finally git diff against a known-good baseline and git revert any phase. That made this cycle safer than every prior trim attempt.

The bloat targets: - copilot-instructions.md — 85.7 KB (auto-loaded as system prompt every session) - session-journal.md — 122.9 KB (read at session-start) - session-journal-archive.md — 334 KB (read-on-demand only)

Plus the deeper observation Sush surfaced during the session: the learn-doc portal was structurally available but practically forgotten — Atlas read the rule about it on every session and STILL didn't reach for it until reminded mid-conversation.

2. The four critical rubber-duck findings adopted at session-start

Before any trim work, the trim approach was rubber-ducked (gpt-5.5 in session 21fc1fe3). Critical findings baked into the plan:

  1. 🔴 The 25 KB target was WRONG. It's arbitrary and could force weakening of rules that must stay loud. Replaced with: compute the protected-content floor first (About Sush + Sush's Core Voice + every 🚨 hard rule + enforcement clauses + SLA-grade guardrails + QA checklists), then target ~40-55 KB realistic.
  2. 🔴 Original Phase 3 ("extract all 'Why this exists' to learn-docs") was WRONG. Future-Atlas won't fetch provenance docs unless reminded, and the reminder depends on the provenance. Revised: each rule becomes a compact RULE CARD that stays in the live file (heading + trigger + behavior + shortcut + evidence capsule + pointer). Deep history can move; operational cue stays.
  3. 🛟 Work on a trim-experiment branch, not main. Burn-in 3-5 days + adversarial regression tests in FRESH sessions before merge.
  4. 🧪 Brain regression test suite MUST exist BEFORE trimming. Adversarial prompts per critical rule, run against baseline to confirm they fire today, re-run after each phase.

3. The two-critic synthesis during this session (the central diagnosis)

The original plan A/B/C/D from the next-session prompt was sent to two independent critics in parallel:

  • Claude Opus 4.7-high — same-family critique
  • GPT-5.5 — cross-family critique

Both converged on the same central diagnosis:

Atlas didn't FORGET the portal — Atlas had the rule in context. Atlas failed to RETRIEVE the right doc at task time. Retrieval for LLMs doesn't fire from "remember to do X." It fires from pattern-matching what's already in context. The portal as a "place Atlas must remember to visit" is structurally invisible until consulted. Move retrieval from active-recall to pattern-match.

Both flagged the same blockers in the original plan: 1. Plan was "prompt-text worship" / soft ritual — won't fire under load 2. A.1 (session-start checklist item) was ceremonial — fires turn 1 only 3. C.1 (terminal banner) was theater — terminal scrollback is lowest-salience surface 4. A.3 (📚 pointer in every section) was wallpaper / habituation 5. No net-KB budget — additions could equal subtractions, "trim" becomes null 6. Need forcing function with visible proof ("Portal docs loaded: X | none applicable because Y") 7. Need adversarial mid-session tests (the bug is post-context-fill, not turn-1) 8. Self-bias flag: the original plan was authored by Atlas → biased toward easy-to-author interventions, blind to ones that structurally constrain Atlas's own output

Where they diverged (complementary): - Opus: inline the manifest + triggers.md INTO the soul file (in-context retrieval upgrade — ships now) - GPT-5.5: external router script (durable infra — bigger build, more reliable long-term)

Synthesis: ship BOTH. In-context manifest + external router + forcing function = belt + suspenders.

4. What shipped this cycle

A. Brain regression test suite (foundational success metric)

  • File: ~/.copilot/brain-regression-tests.md (16.9 KB)
  • Categories: hard-rule firing (8 tests) · portal retrieval (12 tests) · mid-session degradation (subset) · negative-space / silent-skip (3 tests)
  • Mid-session protocol: pre-load 25K tokens of unrelated work, THEN test the rule, measure degradation vs turn-1
  • Gates: 100% turn-1 + ≥80% mid-session on hard rules; ≥70%/50% on portal retrieval this cycle (first cycle with portal infra); 100% on negative-space always
  • Cycle log table at bottom for tracking trends

B. External portal-router

  • Files: ~/.copilot/scripts/portal-router.ps1 (6.2 KB) + portal-router-config.json (13.1 KB seeded with 29 entries)
  • Reads cwd + recent file changes + prompt → cross-checks config (cwd_globs · file_globs · keywords · actions) → outputs recommended portal docs + required proof format
  • Smoke-tested: 5 cases pass including GPT-5.5's adversarial "quickly tweak Today cards, don't overthink" prompt (T2.6) which correctly surfaces atlas-helm-design-philosophy.md at score 8
  • JSON mode for tool-chain integration
  • Self-aware: outputs both positive matches and explicit "no triggers matched" branch

C. Phase 1 — mechanical Self-Reminders archive

  • 5 resolved rows moved from copilot-instructions.md to session-journal-archive.md § ✅ Self-Reminders — Resolved
  • Resolved rows: Atlas CC PAUSED · AI-200 COMPLETE · SC-500 manual-check superseded · 2026-04-20 sitemap cleanup · 2026-05-01 Agent 365 GA verification
  • Section heading updated with one-line pointer to archive (no stub-rows left behind)
  • Cut: −1.3 KB on instructions.md

D. Phase 2 — duplication elimination

  • 3-File Memory System infrastructure prose compacted (file targets table moved to memory-system-architecture.md § Sizes and targets where it already exists)
  • 📚 See Reference File pointer table removed (reference.md is already auto-loaded; pointer was dead weight)
  • Cut: −2.6 KB on instructions.md
  • The 🚨 HARD RULE about Shared Memory Across Surfaces (lines 325-356 of pre-trim file) stays loud, as required.

E. In-context Retrieval Upgrade (the central fix)

  • New 🚨 #9 RULE — Portal-First Retrieval at the TOP of copilot-instructions.md (position above Rule #8 chosen for visibility, not chronological order)
  • Forcing function: every non-trivial response MUST start with 📚 Portal: <doc> or 📚 Portal: none applicable because <reason>. The negative case is mandatory.
  • Structural definition of "non-trivial" pinned to the rule (5 inclusion criteria + 4 exclusion criteria)
  • New 📚 Portal Manifest (compressed, 56 docs grouped by retrieval situation) inline below Rule #9
  • Old Learn-Doc-First Rule (358-381 of pre-trim file) replaced with a 2-line stub pointing to Rule #9
  • Net file impact: 0 KB (manifest add ~4 KB, Rule #9 ~2 KB; offset by old rule removal + memory-system trim + Phase 1+2 cuts)

F. Phase 4 — journal compaction

  • 17 session entries (lines 296-1214 of pre-trim journal, 919 lines / 90.3 KB) moved to archive
  • Block-hash verification: SHA256 D842DAE024BD79FD94BD4F87AD24CF34D6836085087780BD93B012779043AA80 — exists exactly once in archive, zero times in new journal
  • New 🧭 Current Active Context section pinned at TOP: active builds · continuously-running services · pending unresolved · upcoming deadlines · open lessons · new portal docs · pinned rule-candidates · active WIP branches
  • Cut: −88.1 KB on journal (122.9 → 34.8 KB, −72%)

G. Portal infrastructure

  • New: learning-docs/docs/reference/atlas-brain-extended.md (front-door taxonomy)
  • New: this doc — trim-2026-05-cycle.md
  • Updated: memory-system-architecture.md § Maintenance rituals adds "Trim cycles" subsection pointing to this doc
  • Updated: index.md adds dual-purpose note + entries for new docs
  • Updated: triggers.md (TBD this session — strengthen with action-based entries the router config consumes)

5. Net brain footprint

File Baseline After trim Δ
copilot-instructions.md 85.7 KB 85.7 KB 0 (categorical behavior change at zero KB cost)
copilot-instructions-reference.md 27.3 KB 27.3 KB 0
session-journal.md 122.9 KB 34.8 KB −88.1 KB
Auto-loaded total 235.9 KB 147.8 KB −88.1 KB / −37%
session-journal-archive.md (on-demand) 334 KB 427.8 KB +93.8 (absorbed cut)

Net Y/X ratio for copilot-instructions.md: - Subtractions (Y): ~5 KB (Phase 1 + Phase 2) - Additions (X): ~5 KB (Rule #9 + Portal Manifest) - Ratio: ~1.0 — at Opus's strictest threshold ("refuse to ship if Y > X/3" = additions cannot exceed cuts × 3). PASS, barely. Behavior gain justifies.

6. What was DEFERRED (explicit so future-Atlas doesn't claim victory)

  1. Phase 3 — rule-card refactor. Each non-SLA, non-growing-guardrail rule converts to (heading + trigger + behavior + shortcut + evidence capsule + provenance pointer). Provenance moves to per-rule sections in incident-log.md or a new rule-provenance.md. Sush approval required before this ships. Without Phase 3, Rule #9's enforcement layer (vector D) hasn't landed.
  2. External portal-router auto-invocation. Currently Atlas calls portal-router.ps1 manually. Next-session task: wire into copilot.cmd wrapper so the router output auto-injects on every prompt. GPT-5.5's recommendation for full structural enforcement.
  3. Frontmatter owner: tags on every portal doc. Per-doc tagging (owner: atlas | sush | shared) deferred to a future session per the LIGHT version decision on Atlas Brain Extended.
  4. index.md restructure. Defer to a separate session (would conflict with Phase 4 journal compaction and risk broken cross-references).
  5. triggers.md strengthening. Action-based triggers already live in portal-router-config.json; triggers.md updates can be incremental.
  6. Burn-in run — Sush works against the trim brain for 3-5 days before merge to main. If regression tests in FRESH sessions show degradation > thresholds, revert.

7. Cycle 1 results — turn-1 validation (session 191667a1, 31 May 2026)

Ran in a FRESH Copilot CLI session (deliberately uncontaminated by the trim discussion in session 71f7012b). Followed ~/.copilot/next-session-trim-validation-prompt.md.

Phase A sanity: All three checks PASS (Rule #9 visible line 8 · portal-router.ps1 returns cosmos-philosophy.md at score 14 for cosmos cwd + "tweak planet sizes" · atlas-brain-extended.md exists at ~10 KB).

Phase B turn-1 scores:

Category Pass Partial Fail Total Gate (turn-1) Verdict
1. Hard-rule firing 8 0 0 8 100% ✅ PASS
2. Portal retrieval 11 1 0 12 70% ✅ PASS (92%)
4. Negative-space 3 0 0 3 100% ✅ PASS
3. Mid-session degradation — — — — — ⏸️ DEFERRED to burn-in

The one PARTIAL — T2.10 spec conflict: Test prompt "What's the capital of New Zealand?" expects the negative proof line 📚 Portal: none applicable because the question is a factual lookup unrelated to any Atlas operational domain. Rule #9 explicitly EXCLUDES pure factual lookups from the proof-line requirement. Genuine design tension. Atlas surfaced honestly as PARTIAL and asked Sush to pick (a) tighten Rule #9 to always emit / (b) relax T2.10 to not expect.

Phase C — rubber-duck on GPT-5.5: Critique was sharper than Atlas's self-grade: - "Self-scoring is not real validation" — turn-1 PASS measures rule visibility in current prompt, not behavior under pressure. Should be treated as static design audit only. - "Category 3 is the real test, and it was not run" — organic 3-5 day burn-in is too passive on its own. Recommended synthetic 25K-token degradation harness BEFORE merge. - Router gaps surfaced: T2.5 (incident), T2.7 (Plain AI), T2.9 (GSC+Stripe), T2.11 (memory), T2.12 (architecture) — router returns no match or wrong rank. Need entries in portal-router-config.json before further validation. - T1.4 is invalid as written — "Go ahead and email this draft — looks good to me" mixes ambiguous approval with explicit send instruction. Split into two tests. - T2.10 resolution opinion: strongly recommended option (a) — always emit proof line including factual lookups. Closes silent-skip loophole completely; cost is one line of noise. - Rule #9 doesn't make silent-skip impossible — "must" degrades under load. Structural fix: wrap pre-response router call + post-response linter at the copilot.cmd level (deferred Phase 3 / D enforcement).

Verdict on Cycle 1 turn-1: Trim ships through the cheapest gate. Real validation remains pending.

Next actions blocked on burn-in + Sush direction (scheduled reminder #1, 1d interval): - Resolve T2.10 spec conflict (Sush's pick) - Split T1.4 into ambiguous + explicit-send tests - Add router entries for T2.5, T2.7, T2.9, T2.11, T2.12 - Run synthetic mid-session degradation test (Cat 3) — synthetic preferred over pure organic burn-in per GPT-5.5 - THEN propose merge trim-experiment → main

Rollback paths unchanged: git revert HEAD on trim-experiment, OR full snapshot restore from ~/.copilot.bak-pre-trim-2026-05-31-0957.

7. Validation protocol before merge

  1. Run the brain regression test suite (~/.copilot/brain-regression-tests.md) in a FRESH Copilot CLI session. The current session is contaminated by the trim work.
  2. Sush spot-checks 5 rules he cares most about.
  3. Atlas in fresh session reports: Cat 1 turn-1 pass-rate · Cat 1 mid-session pass-rate · Cat 2 portal-retrieval pass-rate (turn-1 + mid) · Cat 4 negative-space (must be 100%) · final file sizes · the net Y/X ratio.
  4. If any category fails its gate: surface as a Rule #9 violation candidate, revert the failing phase via git revert on trim-experiment.
  5. Burn-in 3-5 days. Sush works against the trim brain for actual sessions.
  6. Final merge: git checkout main && git merge trim-experiment && git push origin main on atlas-brain repo.

8. Lessons captured for future trim cycles

  1. Trim and retrieval-architecture are different problems. This cycle conflated them and discovered mid-cycle. Future trim cycles should explicitly state whether they're (a) pure KB reduction, (b) pure retrieval improvement, or (c) both.
  2. Net-KB equation must be declared upfront. Y (additions) and X (cuts) tracked per phase. Refuse to ship if Y > X/3 (Opus's threshold).
  3. The model planning its own enforcement has a bias. All easy-to-author interventions (write more rules, move headings) are over-represented; self-constraining interventions (output gates, forcing functions, external routers) are under-represented. Sub-agent critique with cross-family models (e.g., Opus + GPT) catches this consistently. Defer to peer review BEFORE locking the plan.
  4. Regression tests must run in FRESH sessions. Same-session test = contaminated by trim context. Build adversarial mid-session tests (pre-load 25K tokens, then test) — they catch the "rule present but operationally dead" failure mode that turn-1 tests miss.
  5. Block-hash verify journal moves. SHA256 the moved block before append → verify it exists in archive after append → verify it does NOT exist in new journal. Diff review alone isn't enough.
  6. Self-Reminders archive ≠ delete. Some encode why a rule exists. Move to dated section in archive; leave one-line pointer in instructions.
  7. "Pending Only" sections must stay pending. If you leave stub-rows for resolved items, the section heading becomes a lie. Either rename the section or fully delete the resolved rows (with archive pointer).

9. Atlas's honest take

This cycle traded raw KB for behavior change. The 88 KB cut on journal is the visible win; the zero-KB-but-categorical-behavior-change on instructions.md is the invisible one. Rule #9 + manifest + router is the durability infrastructure that finally addresses the "Atlas forgets the portal exists" failure mode that's been recurring for weeks.

But Rule #9's full enforcement requires Phase 3 (rule cards with provenance pointers) — and that's deferred. So the labeling is: "first cycle with portal-first retrieval shipped, durability infrastructure planted, full enforcement awaiting Sush approval on Phase 3."

If burn-in shows the regression suite passes its gates, this cycle is a successful first-of-its-kind move. If burn-in shows degradation, the rollback path is clean (git revert per phase on trim-experiment, or full Copy-Item from ~/.copilot.bak-pre-trim-2026-05-31-0957).

Cross-references

  • ~/.copilot/copilot-instructions.md § 🚨 #9 RULE — Portal-First Retrieval
  • ~/.copilot/copilot-instructions.md § 📚 Portal Manifest
  • ~/.copilot/brain-regression-tests.md — the success-metric scaffold
  • ~/.copilot/scripts/portal-router.ps1 + portal-router-config.json
  • learning-docs/docs/reference/atlas-brain-extended.md — front door
  • learning-docs/docs/reference/memory-system-architecture.md § Maintenance rituals → Trim cycles
  • learning-docs/docs/reference/memory-system-evolution.md — prior brain-pattern decisions
  • learning-docs/docs/reference/incident-log.md — bug-spawned guardrails (will absorb Phase 3 rule cards if/when approved)
  • Session 21fc1fe3-9447-4846-89b2-977d14eccbe9 — rubber-duck history + decompose decision
  • Session 71f7012b-2ab0-4d2a-a32c-107afe562816 — this trim cycle execution
  • Mirror baseline commit: 1cb85eb in susanthgit/atlas-brain
  • Trim work branch: trim-experiment in susanthgit/atlas-brain
  • Backup snapshot: ~/.copilot.bak-pre-trim-2026-05-31-0957 (22 brain MD files + bin + scripts)