Scan engine phases before a cycle run to predict silent failures. Checks ctx field dependencies, sheet header alignment, code rule violations, and cascade risks.
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Scan engine phases before a cycle run to predict silent failures. Checks ctx field dependencies, sheet header alignment, code rule violations, and cascade risks.
version
1.3
updated
"2026-05-30T00:00:00.000Z"
tags
["engine","active"]
effort
high
disable-model-invocation
true
/pre-mortem โ Engine Health Scan
Skill bag: senior software engineer running pre-cycle silent-failure scan on production-critical infrastructure. The scans below are what that skill checks; the bag adds the discipline of treating gates as gates (CRITICAL = stop, not "stop and continue"), and flagging cascade-risk patterns even when the proximate code looks fine. Full principle: .
The script (ES-7 / G-PM7) runs scans 0, 1, 2, 5 deterministically, driven by the data file .claude/skills/pre-mortem/known_gaps.json (function-name-keyed acknowledged sites โ update the JSON with code changes, never skill prose). Exit codes:0 SAFE TO RUN (no CRITICAL) ยท 1 FIX BEFORE RUNNING (โฅ1 CRITICAL) ยท 2 scan error. Stop the cycle on exit 1.
--since note: auto-derive reads SESSION_CONTEXT's "Last Updated" header. After a same-day session close that date is today, so scan 0 reports "none โ no engine touches" even when commits landed today. Pass --since=<last-cycle-ship-date> to scan a real window.
Real output (C95 shape):
PRE-MORTEM SCAN โ <date>
ENGINE CHANGES SINCE LAST CYCLE: <path-filtered commits, or "none">
CRITICAL: none
WARNINGS (acknowledged off-path or doc drift): <numbered, from known_gaps.json>
CLEAN: Math.random cycle-path 0 unacknowledged; sheet-writes 0 off-list; neighborhoods 0 new stray
NOT AUTO-SCANNED (run from SKILL): ยง3 ctx-deps, ยง4 header alignment, ยง6 write-intent targets
RECOMMENDATION: SAFE TO RUN | FIX BEFORE RUNNING
โ The script does NOT check everything โ scans 3, 4, 6 stay manual
preMortemScan.js covers the deterministic, local, recurrent-friction scans (0/1/2/5). It does not check ctx-field dependencies (ยง3), sheet-header alignment (ยง4), or write-intent targets (ยง6). A SAFE TO RUN from the script means those four scans are clean โ it is not a full pre-mortem. After the script exits 0, run ยง3/ยง4/ยง6 by hand per the procedures below. A gate that silently under-checks is worse than no gate.
What the scans check
Scans 0/1/2/5 below document what the script automates (read them to interpret its output). Scans 3/4/6 are the manual scans you run after the script โ see the โ note above.
0. Engine Code Changes Since Last Cycle (script-automated)
Always run this first. Lists every commit that actually touched engine-path files since the last cycle shipped. Prevents the "nothing has changed, not re-scanning" failure where the skill looks at raw recent commits (which are often docs/journal/terminals) and falsely concludes the cycle path is unchanged. The script does this scan โ the manual form below is a fallback / for interpreting the output.
# Replace <last-cycle-date> with the date the previous edition published.# G-PM2: git pathspec does NOT expand '**' globstar โ enumerate phase dirs literally.
git log --since="<last-cycle-date>" --pretty=format:"%h %ad %s" --date=short \
-- 'phase01-config/*.js''phase02-world-state/*.js''phase03-population/*.js' \
'phase04-events/*.js''phase05-citizens/*.js''phase06-analysis/*.js' \
'phase07-evening-media/*.js''phase08-v3-chicago/*.js''phase09-digest/*.js' \
'phase10-persistence/*.js''phase11-media-intake/*.js' \
'scripts/*.js''lib/*.js''utilities/*.js'
If the filtered list is empty AND the raw git log --since list is also empty, state "no engine touches since last cycle" and proceed. If the filtered list has entries, list them โ every subsequent scan (ctx chain, headers, neighborhoods) must be rerun regardless of any cached "unchanged" memory.
Scan all .js files in phase01-config/ through phase10-persistence/ and utilities/ for any mention of Math.random โ both invocations (Math.random()) and reference-passes (var rng = Math.random;, fn(Math.random)). Both break determinism when they run on the cycle path. The old grep pattern Math\.random\(\) missed reference-pass sites (S166 found three in utilities/utilityFunctions.js that had shipped through every prior cycle run).
CRITICAL โ the file is on the cycle path (invoked by godWorldEngine2.js or any phase function that runs during a cycle). Trace callers if unsure: grep -rn "functionName(" phase*/ scripts/ lib/ --include="*.js".
WARNING (acknowledged, off-path) โ the file is outside the cycle path. Acknowledged sites live in .claude/skills/pre-mortem/known_gaps.json (acknowledgedMathRandom[]), keyed by function name per S230 G-RC5 โ line numbers drift on every refactor (G-PM3), so the JSON carries no line annotations. The script classifies against this file; if reading by hand, grep grep -nE 'function <funcName>|<funcName> = function|<funcName>:' <file> to find the current location. Do not re-list these sites inline here โ the JSON is the single source (a second copy is the drift surface S230 G-RC5 closed). Current entries: civicInitiativeEngine.js#manualRunVote (NOT runManualVote_ โ the old skill name was stale), citizenContextBuilder.js#getCitizensForQuotes, generateChicagoCitizensv1.js#testChicagoCitizenGeneration_ (file disabled S229, retained for reversibility).
CLEAN (defensive throw) โ the mention is inside a throw new Error(...) string for a removed fallback. These are guards, not violations. Files listed in known_gaps.jsondefensiveThrowFiles[]: generationalEventsEngine.js, generateGenericCitizens.js, safeRand.js. (Meta/linter files whose data contains Math.random as a pattern-to-detect are in scanExcludeFiles[] โ e.g. v2DeprecationGuide.js.)
Anything not on the acknowledged or defensive-throw lists is CRITICAL until proven otherwise โ verify by tracing callers back to the engine entry point.
2. Direct Sheet Writes Outside Phase 10 (script-automated)
Scan phase01-config/ through phase09-digest/ for write-only calls: .setValue(, .setValues(, .appendRow(. These should only appear in phase10-persistence/ files. G-PM4: do NOT include getRange or getSheetByName(...).get in the pattern โ getRange(...).getValues() is the canonical READ idiom and matched the old pattern, producing false positives (C95 flagged 3 read-only files). A genuine getRange().setValue() still matches via .setValue(.
Exception list lives in .claude/rules/engine.md. That file enumerates every file authorized to write directly to sheets (Phase 1 engine core, Phase 2 world state, Phase 3 population, Phase 4 event generators/helpers, Phase 5 Tier-5 engines / SL writers / civic / citizen life / citizen generators, Phase 6 tracking, Phase 7 media intake / tracking / helpers, Phase 8 tracking writers, Phase 9 cycle weight, Phase 11 media intake). Phase 40.3 Path 1 audit (S156, commit 76a408c) verified every one โ zero undocumented writers.
Diff the grep result against engine.md's exception list. Any file on the grep that isn't on engine.md is WARNING โ either a new undocumented writer (bug) or a file that needs to be added to engine.md (doc drift). Run /tech-debt-audit if in doubt.
3. ctx Field Dependency Check (MANUAL โ script does NOT check this)
This is the most important check. Phase 5 has 14+ sub-engines that read and write ctx fields. If Engine A reads ctx.summary.careerSignals but Engine B (which writes it) hasn't run yet, the field is undefined.
How to check:
Read phase01-config/godWorldEngine2.js โ find the execution order of all phases and sub-engines
For each Phase 5 sub-engine, scan for ctx.summary.* and ctx.config.* reads
Verify the field was written by a previously-executed engine or phase
Flag any read-before-write as CRITICAL โ this is a silent failure (the engine runs but uses undefined data)
Known dependency chain (verify these are still correct):
Career Engine โ Economic Ripple Engine (via ctx.summary.careerSignals)
Demographics โ Civic Voting, Story Hooks, City Dynamics
4. Sheet Header Alignment (MANUAL โ script does NOT check this)
Check that columns referenced in engine code actually exist in the sheets. Use the service account to read sheet headers:
// Pattern to check: engine code references a column name// Verify it exists in the actual sheet
Read schemas/SCHEMA_HEADERS.md for the canonical column list. Compare against column names used in engine write-intents ({column: value} patterns in Phase 10 files).
Flag any mismatch as WARNING โ column in code but not in sheet means silent data loss.
West Oakland โ Brooklyn (parent inferred from updateCivicApprovalRatings.js DISTRICT_HOODS)
Validation rule: A neighborhood reference is canonical if it appears in EITHER list, OR is a child name in the parent-child mapping. Anything else is a WARNING.
NOT warnings: Eastlake, San Antonio, Glenview, Ivy Hill, Adams Point, Brooklyn, Dimond, Grand Lake (all valid world-state children); KONO, Lake Merritt, Uptown (all valid canon-parents).
WARNINGS: anything outside both lists, e.g. Coliseum District (transit area, not a neighborhood), Elmhurst, Jingletown, HH-KEANE (household ID leaked into Neighborhood column). (East Oakland canonized S328 โ Mike-direct: legit Oakland land mass, no longer a stray.)
6. Write-Intent Target Validation (MANUAL โ script does NOT check this)
Scan Phase 10 persistence files for write-intent processing. Check that every target sheet name referenced in write-intent handlers matches an actual sheet. A write-intent targeting a non-existent sheet is a silent failure โ the data just disappears.
Output Format
PRE-MORTEM SCAN โ [Date] | Cycle [N]
================================================
ENGINE CHANGES SINCE LAST CYCLE:
[list of path-filtered commits, or "none" with proof]
CRITICAL (will cause silent failures in the cycle):
1. [file:line] โ Math.random reference-pass in <cycle-path file>#<fn> (on cycle path, not in known_gaps.json acknowledged list)
2. [file:line] โ ctx.summary.careerSignals read in economicRippleEngine.js:23 before runCareerEngine.js executes
WARNINGS (acknowledged off-path or doc drift):
3. [file:line] โ Column "HousingStress" in householdFormationEngine.js not found in SCHEMA_HEADERS.md
4. [file:line] โ Math.random in civicInitiativeEngine.js#manualRunVote โ manual-vote path, outside cycle (acknowledged in known_gaps.json)
5. [file:line] โ Neighborhood "Coliseum District" in someFile.js:89 not in canon-12 OR Neighborhood_Map 17 OR child-mapping
CLEAN:
- Math.random cycle-path: 0 violations
- Sheet writes outside Phase 10: all on engine.md exception list
- ctx dependencies: all verified
- Sheet headers: all aligned
- Neighborhoods: all canonical
================================================
RECOMMENDATION: [SAFE TO RUN | FIX BEFORE RUNNING]
If SAFE TO RUN but warnings exist, list them verbatim under the recommendation so the next cycle inherits the open items.
Known Gaps (do not re-surface as CRITICAL unless scope changes)
Mirror of engine-repair items parked until the priority says otherwise โ a different class from the scan-classification data in known_gaps.json (which holds the acknowledged Math.random / neighborhood-literal sites). These are backlog notes, not scan input.
Verify against current state before treating any entry here as acknowledged. A stale "known gap" teaches the operator to disbelieve the scan (the G-PM1 lesson): the old utilities/utilityFunctions.js:29,36,53 Math.random entry sat here ~60 sessions after the fix actually shipped (v2.15, S180 โ pickRandom_/pickRandomSet_/maybePick_ now require an rng param and throw; zero Math.random invocations remain). It was removed S246/RB-5. If the scan ever flags one of these, re-confirm the code still matches the note before downgrading to WARNING.
Off-cycle Math.random sites โ see known_gaps.jsonacknowledgedMathRandom[] (canonical), summarized in ยง1.
62-first/53-last name clustering in citizen generators (ENGINE_REPAIR P1).
