sync-codex

name	sync-codex
description	[Codex] Use when you need to run the full Codex mirror sync + verify pipeline (migrate → hooks → context → verify) standalone, no npm/package JSON needed.
disable-model-invocation	false

Codex compatibility note:

• Invoke repository skills with $skill-name in Codex; this mirrored copy rewrites legacy Claude /skill-name references.
• Task tracker mandate: BEFORE executing any workflow or skill step, create/update task tracking for all steps and keep it synchronized as progress changes.
• User-question prompts mean to ask the user directly in Codex.
• Ignore Claude-specific mode-switch instructions when they appear.
• Strict execution contract: when a user explicitly invokes a skill, execute that skill protocol as written.
• Subagent authorization: when a skill is user-invoked or AI-detected and its protocol requires subagents, that skill activation authorizes use of the required spawn_agent subagent(s) for that task.
• Do not skip, reorder, or merge protocol steps unless the user explicitly approves the deviation first.
• For workflow skills, execute each listed child-skill step explicitly and report step-by-step evidence.
• If a required step/tool cannot run in this environment, stop and ask the user before adapting.

Codex Project-Reference Loading (No Hooks)

Codex uses static project-reference loading instead of runtime-injected project docs. When coding, planning, debugging, testing, or reviewing, open project docs explicitly using this routing.

Always read:

• docs/project-config.json (project-specific paths, commands, modules, and workflow/test settings)
• docs/project-reference/docs-index-reference.md (routes to the full docs/project-reference/* catalog)
• docs/project-reference/lessons.md (always-on guardrails and anti-patterns)

Missing/stale context route: If docs/project-config.json, the docs index, lessons.md, CLAUDE.md, AGENTS.md, or any task-required reference doc is missing or stale, auto-run $project-init or the narrow setup route ($project-config, $docs-init, $scan-all, $scan --target=<key>, $claude-md-init) before ordinary project-specific work. If Codex mirrors or AGENTS.md are missing/stale, ask the user to run $sync-codex; do not auto-run it.

Situation-based docs:

• Project structure/architecture/tech-stack/deployment/setup (any layer — backend, frontend, or infra): project-structure-reference.md
• Backend/CQRS/API/domain/entity changes: backend-patterns-reference.md, domain-entities-reference.md
• Frontend/UI/styling/design-system: frontend-patterns-reference.md, scss-styling-guide.md, design-system/README.md
• Spec authoring, docs/specs/ pathing, or TC format: feature-spec-reference.md, spec-system-reference.md, spec-principles.md
• Behavior/public-contract changes or spec-test-code sync: workflow-spec-test-code-cycle-reference.md plus the spec docs above
• Derived spec indexes/ERDs/reimplementation guides: spec-system-reference.md and source Feature Specs under docs/specs/
• Integration test implementation/review: integration-test-reference.md
• E2E test implementation/review: e2e-test-reference.md
• Code review/audit work: code-review-rules.md plus domain docs above based on changed files

Do not read all docs blindly. Start from docs-index-reference.md, then open only relevant files for the task.

Quick Summary

Goal: Run the full Codex mirror pipeline standalone — equivalent to npm run sync:all && npm run verify:all (sync + verify) without package.json or npm. This runner is the single source of truth for the pipeline; the package.json sync:all/verify:all scripts delegate to it, so a project that only copied .claude (no root package.json) runs the identical pipeline.

Renamed: formerly /codex-sync — that name no longer resolves as a slash command; use $sync-codex.

Also bootstraps team-wide Codex completion notifications by copying the portable .claude/scripts/codex/codex-notify.mjs helper into .codex/scripts/codex/ and upserting notification plus TUI status-line keys into .codex/config.toml.

Workflow:

1. Run — node .claude/skills/sync-codex/scripts/run-codex-sync.mjs
2. Verify — Exit code 0 = pass; check stdout summary
3. Inspect — On failure, re-run failing stage manually with --only=<stage> and --verbose

Key Rules:

• MUST run all 16 stages in order — orchestrator fails fast on first non-zero exit
• NEVER edit .agents/skills/sync-codex/** (auto-mirror) — edit .claude/skills/sync-codex/** source instead
• .claude is the source for skills/workflows/hooks; generated acceptance targets are .agents/skills/**, .codex/CODEX_CONTEXT.md, and AGENTS.md
• Stages 1-3 mutate .agents/skills/, .codex/, AGENTS.md; stages 4-16 are read-only verifiers (codex tooling tests, repo-script unit tests, 3 hook-suite gates, the 7 codex verifiers, and the cross-surface divergence oracle)
• Stage 1 upserts [tui].status_line to show model+reasoning, current directory, project root, context used, five-hour limit, and weekly limit by default
• Stage 3 mirrors full CLAUDE.md into AGENTS.md, then appends the generated Codex hook/context mirror and shared AI-SDD markers so Codex has both source instructions and hookless parity context
• Stage 1 must not inline docs/project-reference/lessons.md content into .agents/skills/**; generated skill mirrors reference the project-reference loading gate instead
• The SYNC:ai-sdd-artifact-contract marker must appear after sync in .codex/CODEX_CONTEXT.md and AGENTS.md
• No npm dependency — pure node + spawned subprocesses
• Idempotent — safe to re-run; second run produces only timestamp diffs

Bootstrap Gate (when AGENTS.md is missing or incomplete)

This skill is the route the agent-files bootstrap gate offers for a missing — or incomplete — root AGENTS.md, the generated Codex mirror of CLAUDE.md. Because Codex has no hooks, the universal session-start guides must be embedded in AGENTS.md directly; stage 3 produces that mirror (full CLAUDE.md copy, so the <!-- CK:UNIVERSAL-GUIDES v1 --> sentinel propagates) + hookless-parity context.

"Incomplete" means the file exists but lacks the universal guides — same three-state detection as the CLAUDE.md route (missing → init, incomplete → update smart-merge preserving project content, ok → no block), decided by the shared sentinel-then-anchors check.

Detection is shared with the CLAUDE.md route via .claude/hooks/lib/agent-files-state.cjs. Opt out of completeness enforcement with portability.requireUniversalGuides: false in docs/project-config.json (default true); skip init dismisses both hooks for 24h. Generate CLAUDE.md first (via $claude-md-init) — stage 3 reads it as the mirror source.

Stages

16 stages, sequential — the full npm run sync:all && npm run verify:all pipeline (the npm scripts delegate here). Stages 1-3 mutate; 4-16 verify (read-only):

#	Stage	Script	Effect
1	migrate	.claude/scripts/codex/migrate-claude-to-codex.mjs	Migrate Claude agents → .codex/agents/; mirror skills → .agents/skills/; setup Codex notifications
2	hooks	.claude/scripts/codex/sync-hooks.mjs	Generate .codex/hooks.json + sync report
3	context	.claude/scripts/codex/sync-context-workflows.mjs	Regenerate .codex/CODEX_CONTEXT.md + AGENTS.md with workflow context and shared AI-SDD markers
4	tests	node --test .claude/scripts/codex/tests/*.test.mjs	Run codex tooling unit tests
5	scripts-tests	node --test .claude/scripts/tests/*.test.mjs	Run repo-script unit tests (statusline widgets, etc.)
6	hooks-count-drift	.claude/hooks/tests/run-all-tests.cjs --filter=count-drift	Verify the <!-- COUNT:… --> inventory markers have not drifted from the real skill/hook/agent/workflow counts
7	hooks-parity	.claude/hooks/tests/run-all-tests.cjs --filter=parity	Verify hook parity across the Claude/Codex/Copilot surfaces
8	hooks-doc-sync	.claude/hooks/tests/run-all-tests.cjs --filter=doc-sync-gate	Verify hook documentation stays in sync with the wired hook set
9	wf-cycle	.claude/scripts/codex/verify-workflow-cycle-compliance.mjs	Verify workflow sequence cycle compliance
10	sk-proto	.claude/scripts/codex/verify-skill-protocol-compliance.mjs	Verify skill strict-execution-contract
11	residue	.claude/scripts/codex/verify-no-project-residue.mjs	Verify no project residue in generated and generic source artifacts
12	sdd	.claude/scripts/codex/verify-sdd-semantic-compliance.mjs	Verify AI-SDD semantic contract coverage
13	review-validate-coverage	.claude/scripts/codex/verify-review-validate-coverage.mjs	Verify every review-family skill carries the $why-review --validate-findings route; graders never embed the fix-loop (Self-Review Convergence Loop sensor)
14	sync-adoption-parity	.claude/scripts/codex/verify-sync-adoption-parity.mjs	Verify SYNC tag ↔ carrier adoption parity: declared carriers carry both main + :reminder blocks, no undeclared skill carries a matrix tag, every injected body byte-matches canonical
15	provenance-markers	.claude/scripts/codex/verify-provenance-markers.mjs	Verify provenance-marker discipline in architecture-knowledge.md: declared tags only · — VERIFY only on a declared tag · §3/§8/§9/§10 each carry a default-basis banner · no banner enumerates row-level exceptions · a [model-knowledge] marker carries — VERIFY. Fail-soft when the catalog is absent
16	sync-divergence	.claude/scripts/codex/verify-sync-divergence.mjs	Byte-equality oracle: .agents/skills mirror === .claude/skills (codex mirror)

Usage

# Full sync (standalone, no npm):
node .claude/skills/sync-codex/scripts/run-codex-sync.mjs

# Stream live child output:
node .claude/skills/sync-codex/scripts/run-codex-sync.mjs --verbose

# Full sync while forcing skill copy mode:
node .claude/skills/sync-codex/scripts/run-codex-sync.mjs --copy-skills

# Read-only verifiers (no mutation) — the full `npm run verify:all`:
node .claude/skills/sync-codex/scripts/run-codex-sync.mjs --only=tests,scripts-tests,hooks-count-drift,hooks-parity,hooks-doc-sync,wf-cycle,sk-proto,residue,sdd,review-validate-coverage,sync-adoption-parity,provenance-markers,sync-divergence

# Skip stages while debugging:
node .claude/skills/sync-codex/scripts/run-codex-sync.mjs --skip=migrate,hooks

Exit codes: 0 all pass · 1 orchestrator failure · non-zero propagates from failing stage.

AI Mistake Prevention — Failure modes to avoid on every task:

Re-read files after context changes. Context compaction, resume, or long-running work can make memory stale; verify current files before acting. Verify generated content against source evidence. AI hallucinates APIs, names, claims, and document facts. Check the relevant source before documenting or referencing. Check downstream references before deleting or renaming. Removing an artifact can stale docs, generated mirrors, configs, and callers; map references first. Trace the full impact chain after edits. Changing a definition can miss derived outputs and consumers. Follow the affected chain before declaring done. Verify ALL affected outputs, not just the first. One green check is not all green checks; validate every output surface the change can affect. Assume existing values are intentional — ask WHY before changing. Before changing a constant, limit, flag, wording, or pattern, read nearby context and history. Surface ambiguity before acting — don't pick silently. Multiple valid interpretations require an explicit question or stated assumption with risk. Keep shared guidance role-relevant. Universal guidance must help every receiving skill or agent; code-specific obligations belong only in code-specific protocols.

Closing Reminders

Protocols in force (concise digest of the SYNC/shared blocks this skill carries) — MUST ATTENTION each canonical body below still binds:

• AI Mistake Prevention: verify generated content against evidence, trace downstream references, verify all affected outputs, re-read after context loss, surface ambiguity.
• Critical Thinking: traced file:line proof per claim, confidence >80% to act, never guess.

MUST ATTENTION invoke ONLY when user explicitly requests codex sync — never auto-invoke MUST ATTENTION edit source .claude/skills/sync-codex/**, NEVER the .agents/skills/sync-codex/** mirror MUST ATTENTION keep .codex/scripts/codex/codex-notify.mjs generated from .claude/scripts/codex/codex-notify.mjs; edit the .claude source first MUST ATTENTION keep Codex config upserts surgical; preserve unrelated .codex/config.toml keys and tables while updating the managed notification/status-line keys MUST ATTENTION keep AGENTS.md sync comprehensive; mirror full CLAUDE.md plus generated hook/context blocks, and preserve unmanaged AGENTS.md preface text MUST ATTENTION keep learned-lessons content out of .agents/skills/**; skills may point to docs/project-reference/lessons.md but must not embed its entries MUST ATTENTION orchestrator fails fast — re-run single failing stage with --only=<id> --verbose to debug MUST ATTENTION working directory auto-resolves to repo root from script path — do not pass --cwd MUST ATTENTION stages 1-3 mutate; stages 4-16 verify only — use --only= for non-destructive validation

Anti-Rationalization:

Evasion	Rebuttal
"Just edit the .agents mirror directly"	Next sync overwrites it. Always edit .claude/skills/sync-codex/ source
"Skip a stage to save time"	Verifiers (4-16) catch drift; skipping = silent regression risk
"Sync looks idempotent, skip verify"	Timestamp diffs are normal; structural diffs = bug. Always run verifiers

[FAILS FAST] First non-zero stage exit aborts chain. Re-run failing stage manually to debug. [REPO ROOT] Orchestrator auto-resolves repo root from its own path. NEVER pass --cwd.

Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.

MUST ATTENTION apply critical + sequential thinking — every claim needs appropriate traced evidence (file:line for repo/code claims; source URL or artifact section for research, product, content, and docs claims); confidence >80% to act, <60% DO NOT recommend. Anti-hallucination: never present guess as fact, admit uncertainty freely, cross-reference independently, stay skeptical of own confidence.

MUST ATTENTION apply AI mistake prevention — verify generated content against evidence, trace downstream references before deleting or renaming, verify all affected outputs, re-read files after context loss, and surface ambiguity before acting.

Hookless Prompt Protocol Mirror (Auto-Synced)

Source: .claude/.ck.json + .claude/skills/shared/sync-inline-versions.md (:full blocks) + .claude/scripts/lib/hookless-prompt-protocol.cjs

[WORKFLOW-EXECUTION-PROTOCOL] [BLOCKING] Workflow Execution Protocol — MANDATORY IMPORTANT MUST CRITICAL. Do not skip for any reason.

Generic portability boundary: Reusable skills and protocol text stay project-neutral; project-specific conventions are discovered from docs/project-config.json and docs/project-reference/. Apply shared AI-SDD from shared/sdd-artifact-contract.md. Read docs/project-config.json and docs/project-reference/docs-index-reference.md, then open the project reference docs named there. For spec, test-case, behavior-change, public-contract, or docs/specs/ work, route through the local spec docs named by the docs index: feature-spec-reference.md, spec-system-reference.md, spec-principles.md, and workflow-spec-test-code-cycle-reference.md when specs/tests/code must stay synchronized. If either file or a required reference doc is missing or stale, auto-run $project-init (or the narrow lower-level route such as $project-config, $docs-init, $scan-all, or $scan --target=<key>) before ordinary project-specific work. Any supported AI tool may execute when this shared context and local docs are available.

1. DETECT: If the prompt starts with an explicit slash skill/workflow command, execute it directly. Otherwise match the prompt against the workflow catalog and skill list.
2. ANALYZE: Choose the best option: execute directly, invoke a skill, activate a standard workflow, or compose a custom step combination.
3. AUTO-SELECT: Pick the best option yourself. Do not ask the user to choose between direct execution, skill, standard workflow, or custom workflow.
4. ACTIVATE: For a selected workflow, call $start-workflow <workflowId>; for a selected skill, invoke that skill; for a custom workflow, sequence custom steps directly; for direct execution, proceed with the task.
5. CREATE TASKS: task tracking for ALL workflow/skill/custom steps before execution when the selected path has multiple steps.
6. EXECUTE: Advance per the Workflow Step Advancement & Parallel Phases rule in your context instructions — model-driven; a sub-agent completion advances a step identically to an inline call; a parallel-phase group is an all-return barrier (advance only after ALL members return, never serialize it)

Shared AI-SDD Protocol Markers

Source: .claude/skills/shared/sync-inline-versions.md

SYNC:ai-sdd-artifact-contract

AI-SDD Artifact Contract — Shared spec-driven development rules stay portable and source-owned.

1. Keep reusable AI-SDD principles in .claude; put repository-specific paths, commands, owners, products, and formats in project config/reference docs.
2. Preserve cycle: spec -> plan -> tasks -> implement -> verify -> update spec/docs.
3. Trace every requirement or invariant through decision, task, TC/test, source evidence, and docs/spec update.
4. Treat code-to-spec extraction as reference-only until accepted by the canonical spec owner.
5. Any supported AI tool may plan, implement, review, or verify with synced context; using multiple tools is optional.
6. Update .claude source first, then sync generated mirrors; do not manually edit .agents, .codex, or AGENTS.md. — why: mirrors are generated artifacts; hand-edits are overwritten on the next sync
7. If docs/project-config.json, root instruction files, or a required project-reference doc is missing or stale, auto-run $project-init or the narrow lower-level route before ordinary project-specific work.

Active reference: shared/sdd-artifact-contract.md in the active skills root.

---

SYNC:ai-sdd-artifact-contract:reminder

• MANDATORY Apply shared/sdd-artifact-contract.md; keep reusable AI-SDD in .claude and local rules in project docs.
• MANDATORY Code-to-spec extraction is reference-only until canonical acceptance; any supported AI tool may execute with synced context.
• MANDATORY Update .claude source before syncing generated mirrors; do not manually edit .agents, .codex, or AGENTS.md.
• MANDATORY Missing or stale project config, root instruction files, or required reference docs route project-specific work through $project-init or the narrow setup route automatically. [TASK-PLANNING] [MANDATORY] BEFORE executing any workflow or skill step, create/update task tracking for all planned steps, then keep it synchronized as each step starts/completes.

[LESSON-LEARNED-REMINDER] [BLOCKING] Task Planning & Continuous Improvement — MANDATORY. Do not skip.

Break work into small tasks (task tracking) before starting. Add final task: "Analyze AI mistakes & lessons learned".

Extract lessons — ROOT CAUSE ONLY, not symptom fixes:

1. Name the FAILURE MODE (reasoning/assumption failure), not symptom — "assumed API existed without reading source" not "used wrong enum value".
2. Generality test: does this failure mode apply to ≥3 contexts/codebases? If not, abstract one level up.
3. Write as a universal rule — strip project-specific names/paths/classes. Useful on any codebase.
4. Consolidate: multiple mistakes sharing one failure mode → ONE lesson.
5. Recurrence gate: "Would this recur in future session WITHOUT this reminder?" — No → skip $learn.
6. Auto-fix gate: "Could $code-review/$code-simplifier/$security-review/$lint catch this?" — Yes → improve review skill instead.
7. BOTH gates pass → ask user to run $learn. [CRITICAL-THINKING-MINDSET] Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination principle: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination. AI Attention principle (Primacy-Recency): Put the 3 most critical rules at both top and bottom of long prompts/protocols so instruction adherence survives long context windows. Goal-driven execution: Define success criteria first, loop until verified, and stop only when observable checks pass. Tests verify intent: Tests must protect business rules/invariants and fail when the protected intent breaks, not only mirror current behavior.

Common AI Mistake Prevention (System Lessons)

• Re-read files after context compaction. Edit requires prior Read in same context; compaction wipes read state. Re-read before editing.
• Grep for old terms after bulk replacements. AI over-trusts find/replace completeness. Grep full repo after bulk edits for missed refs in docs/configs/catalogs.
• Check downstream references before deleting. Deletions cascade doc/code staleness. Map referencing files before removal.
• After memory loss, check existing state before creating new. Compaction wipes prior-work memory. Query current state to resume — never blindly duplicate.
• Verify AI-generated content against actual code. AI hallucinates APIs, class names, method signatures. Grep to confirm existence before documenting/referencing.
• Trace full dependency chain after edits. Changing a definition misses downstream consumers. Trace the full chain.
• When renaming, grep ALL consumer file types. Some file types silently ignore missing refs (no compile error). Search code, templates, configs, generated files.
• Trace ALL code paths when verifying correctness. Code existing ≠ code executing. Trace early exits, error branches, conditional skips — not just happy path.
• Update docs that embed canonical data when source changes. Docs inlining derived data (workflows, schemas, configs) go stale silently. Update all embedding docs alongside source.
• Verify sub-agent results after context recovery. Background agents may finish while parent compacted — grep-verify output, don't trust assumed completion.
• Cross-check full target list against sub-agent assignments. Parallel sub-agents by category miss boundary items. Reconcile union of assignments against target list before proceeding.
• Sub-agents inherit knowledge only from their agent .md definition — use custom agent types, not built-in Explore. Tool adoption = permission + knowledge + enforcement (numbered workflow step).
• Persist sub-agent findings incrementally, not as a final batch. Long sub-agents hit cutoffs before final write — findings lost. Instruct append-per-section to report file.
• When debugging, ask "whose responsibility?" before fixing. Trace caller (wrong data) vs callee (wrong handling). Fix at responsible layer — never patch symptom site.
• Test failure → adjudicate WHO is at fault (source vs test) before forcing green. A green-again suite is not the goal; the correct verdict on what was actually wrong is. Root-cause first, then triangulate the failure against the governing spec (docs/specs/** if one exists) AND the source: SOURCE-WRONG → fix code at the owning layer and keep/strengthen the test; TEST-WRONG → fix the stale assertion/setup at its root. NEVER weaken an assertion, add a skip, or relax a timeout to force green, and never change source to satisfy a broken test. Spec silent or ambiguous about which side is correct → STOP and ask the user.
• Grep ALL removed names after extraction/refactoring. Primary file "done" ≠ secondary files clean. Grep entire scope for every removed symbol before declaring complete.
• Assume existing values are intentional — ask WHY before changing. Pattern-matching as "wrong" skips context. Before changing any constant/limit/flag: read comments, git blame, surrounding code.
• Verify ALL affected outputs, not just the first. One build green ≠ all green. Multi-stack changes (backend/frontend/tests/docs) require verifying EVERY output.
• Evaluate fit before copying a nearby pattern. Closest example ≠ matching preconditions — verify the new context shares the same constraints, base classes, scope, lifetime.
• Holistic-first debugging — resist nearest-attention trap. Don't dive into first plausible cause. List EVERY precondition (config, env vars, paths, DB, endpoints, creds, versions, DI, data). Verify each against evidence (grep/query — not reasoning). Ask "what would falsify this?" — if nothing, it's not a hypothesis. Most expensive failure: going deeper in "obvious" layer while bug sits in layer never questioned.
• Surgical changes — apply the diff test (context-aware). Two modes: (1) Bug fix → every line traces to the bug; no restyling; orphan cleanup only for imports YOUR changes made unused. (2) Review/enhancement → implement improvements AND announce as "Enhancement beyond main request: [what]". Never silently scope-creep. Diff test: "Would this line exist if I wasn't asked to do X?" — if no, delete or announce.
• Surface ambiguity before coding — don't pick silently. Multiple valid interpretations → present each with effort: "[Request] could mean (1) [N h], (2) [N h]. Which matters?" List scope/format/volume/constraints assumptions first. If simpler path exists, say so. Never silently pick.
• [MANDATORY FIRST ACTION] ALWAYS activate a suitable skill or workflow BEFORE responding. Match task against workflow catalog + skill list; invoke via skill invocation or $start-workflow <workflowId>. NEVER answer or write code before checking. Skip = protocol violation.
• Why-Review adversarial mindset — apply when reviewing any plan, decision, or design. Default SKEPTIC not VALIDATOR: steel-man a rejected alternative, invert each stated reason ("what does it sacrifice?"), stress-test top 2-3 assumptions, run pre-mortem ("ships, fails in 3 months — what breaks?"), surface 1-2 alternatives author missed. Section presence ≠ quality; quality = causal reasoning + concrete mitigations + evidence, not "it's better" or "monitor closely".
• Front-load report-write in sub-agent prompts for large reviews. Many-file sub-agents hit budget before final write — findings lost. Design prompts so: (1) report-write is first explicit deliverable, (2) append per-file/section (not batched), (3) scope bounded so reads don't exhaust budget. Truncated mid-sentence with no report file → spawn narrower scope, don't retry same prompt.
• After context compaction, re-verify all prior phase outcomes before continuing. Summaries describe intent, not environment state (git index, filesystem, processes). On resume, FIRST audit: git status, re-read modified files, verify filesystem. Every "completed" claim is an untested hypothesis until evidence confirms.
• OOM/memory: check row count before row size. Triage: (1) Unbounded query — no DB filter for trigger? Push filter to DB; eliminates OOM. (2) Large rows? Projection reduces proportionally. Row reduction > projection in ROI.
• Keep domain concepts out of generic/shared/infrastructure layers. Reusable layer (shared library, framework, infra module) must reference NO consumer-specific domain concept — tenant/customer/product IDs, business entities, feature rules. Leak compiles + runs → passes review silently while coupling the "reusable" layer to one consumer. Keep shared type domain-free; push domain fields/logic down into the consumer via subclass/composition. — why: a layer coupled to one consumer's domain is no longer reusable.