Build Loop

Build-Loop — the per-feature build→review discipline

You are running the loop the harness already runs but never wrote down (cartograph/STATE.md:37, cartograph/PLAN-oracle-reviewer.md). It is a CONDUCTOR: each phase delegates to an existing artifact and clears a falsifiable GATE before the next. Reimplement nothing. The cost of skipping it is the green-but-wrong build (STATE.md:41 — 3 bugs survived green unit tests, caught only in practice) and the re-prompting tax this skill exists to remove.

Canonical token (use these exact phase names everywhere): align → criteria → red tests → pre-build review → build to green → post-build review → verify in practice → capture → ship.

The funnel (phase · falsifiable gate · who owns it)

0. ALIGN ON INTENT. Before anything, confirm you understand what the user actually wants and the payoff they picture. If the request is ambiguous or you are inferring, ASK (AskUserQuestion, one decision per turn) — a full build on an unconfirmed interpretation is confident-wrong and gets cut wholesale. GATE: success criteria are CONFIRMED by the user, not inferred. Do NOT auto-fire phases 2+ until this passes, even under an explicit "build it".
1. CRITERIA & PREDICT. State falsifiable success criteria; log the load-bearing prediction. → skill calibration. First run cartograph/extract.py --query governed-by <target> (Decision D, create-vs-update): a HIT means a spec: already governs this file — READ the criteria from its requirements: EARS clauses and STRENGTHEN that binding; a MISS means write criteria inline (optionally author a new binding). GATE: a prediction id is logged whose --expect ties ≥1 clause to something you did NOT author (user-confirmed intent / external check), per calibration's self-confirming---expect trap.
2. RED TESTS (example + property). Before a line of production code, write BOTH example/unit tests (pin known cases) AND property/invariant tests derived from the spec's INTENT (one property per intent clause whose falsification = green-but-wrong). Run them; confirm they FAIL. GATE: tests exist and are RED before any impl. → references/property-tests.md.
3. PRE-BUILD REVIEW. Spawn a fresh-context reviewer on the criteria + RED tests BEFORE building: does the spec match intent (intent-fit, not just code-correctness)? under-build? over-build / out-of-scope (a finding, not a bonus)? → agent critic (give it ONLY the request + criteria + test paths, never your reasoning). GATE: the critic's verdict is addressed; a wrong criterion is fixed while it is still cheap.
4. BUILD TO GREEN. Write code until the full suite passes — cold, not cached. On the SECOND identical failure, → skill stuck-detection (stop, switch strategy class, don't re-parameterize). GATE: full suite green in a clean run.
5. POST-BUILD REVIEW → VERIFY IN PRACTICE. FIRST, after cold-green and BEFORE the live run, spawn a fresh-context reviewer on the IMPLEMENTATION (not the spec): the phase-3 critic reviewed tests that had no code to be wrong yet, so green + a happy-path run can still hide a green-but-wrong impl. → agent critic; for an enforcement-layer change the harness-auditor is MANDATORY. Treat a suggested FIX as a HYPOTHESIS, not a patch — apply it against the FULL suite, since a fix aimed at one finding can violate a contract another test pins; bind every confirmed finding with a regression test. THEN run the real thing end-to-end — the actual tool / trigger / environment, not a proxy → builtin /verify, and score the load-bearing prediction on the REAL path. GATE: impl-review findings are regression-bound + addressed, AND the prediction scores hit on the real path (green gates verify the ARTIFACTS; only the live run verifies the CLAIM — calibration). (session 21078e9b, 2026-06-23: every pre-build critic found only test-coverage gaps; ALL real code bugs — 2 selection-follow bugs + 3 enforcement-guard bypasses — surfaced only in the post-build impl critic + auditor, and one critic's own suggested fix broke a contract a prior test caught; prediction 6b1e4a12 missed exactly the 'reviews force no rework' clause.) TRUNK-DRIFT on a tracked-tree invariant (a coverage / "every X is wired" / lockfile / manifest check that enumerates tracked files): local-green does NOT predict CI-green — CI grades your branch MERGED WITH CURRENT main, so a peer who landed state after you branched flips it RED on inputs you never saw locally. Under a known-active concurrent peer (multiple live sessions / a worktree holding main): make THAT the prediction's residual risk (not a generic OS-portability hunch), and before merge re-fetch + rebase onto origin/main and re-run the full suite on the rebased tree so local == CI's merged view. (session 37226faa, 2026-06-23: a CI-coverage guard went RED on 3 tests a concurrent mission-control merge added to main mid-build; local full-suite-green missed them; prediction 970bdc74 named the wrong residual risk.) PLACEHOLDER-METADATA HONESTY (a named green-but-wrong class): when the build ships placeholder/generated assets, any displayed metadata about them (durations, sizes, counts) must be DERIVED from — or mechanically TEST-BOUND to — the actual files; never free-floating hand-written values. Hand-authored metadata drifts to the aspirational final state, and structural/BDD tests compare data files to each other, never to the binary assets, so the whole suite stays green while the product lies. Exactly what the fresh-context critic catches — brief it on the RAW source + the user's verbatim goal ("judge only what exists"), not on derived docs. (2026-07-01, session 54794ff2: catalog said 3:47, placeholder audio ended ~1:10; survived 133 tests + 14-check e2e; caught by critic. First fix hand-SYNCED values — a sync, not a derivation; the class stayed open until a test binding catalog durations to the WAV headers landed the same session.) A FRESHLY WRITTEN E2E DRIVER IS ITSELF UNTESTED CODE: on a first-run failure the default hypothesis is driver miscalibration, not a product bug. Two recurring driver errors: (1) one-shot asserts on async state — poll to a deadline instead of sampling once (media needs load time); (2) asserting state written only by an event the script never triggered (a best-score persisted only at game-over — the drive must actually lose first). Read the implementation's state-write points BEFORE touching product code. House the driver in the repo (tests/e2e/ + dev dep + npm script), never a scratchpad — temp dirs can't resolve the repo's node_modules, and the drive must persist as the fix-round's rerunnable gate. (2026-07-01, session 54794ff2: 12/14 → 14/14 with zero product changes.)
6. CAPTURE. If the result recurs, was correction-born, or encodes taste the user articulated, snapshot it. → skill eval-capture + /run-evals (passes day-one). Where a spec governs the target (phase-1's governed-by check), write the eval-corpus case into the governing spec's — or the satisfied requirement's — verified_by:, and ensure that case EXISTS or the dangling-spec gate blocks; a status: shipped spec needs every requirement carrying a resolving verified_by or untested-requirement blocks (extract.py --check). GATE: a corpus case is green today, or a conscious skip is stated.
7. SHIP. Branch + PR. Harness-artifact changes → /harness-pr (lint, auditor, body template, human merges). GATE: on a branch, prediction scored, PR opened.

When to run it

Auto-trigger on ANY non-trivial build/feature/fix/refactor — anything that produces shippable code, changes behavior, or has a definition of done — the MOMENT phase-0 intent is confirmed. Don't wait to be told; being re-prompted is the miss this skill closes. SKIP: trivial one-liners, pure lookups, doc-only edits, read-only analysis. Under-firing returns you to re-prompting; over-firing taxes quick tasks — phase 0's confirm-gate is what stops it firing on an ambiguous ask.

Verifying on this Windows checkout (cp1252)

Ad-hoc python3 -c "...open()..." verify one-liners default to cp1252 here and crash two ways: READING a byte undefined in cp1252 (e.g. 0x8f, from open(f).read()), and PRINTING a char cp1252 can't encode (arrows →, em-dashes, CJK from ledger data) to a strict console. It bites in phases 4–5 AND on the late ship commands (push/PR/score), where it is easy to drop the flag after a clean run. Prefix EVERY inline-python verify command with PYTHONUTF8=1; to read a file's contents prefer python3 -m py_compile <f> over open(f).read(). This is the THROWAWAY-command side; making a COMMITTED script robust (open(encoding="utf-8"), reconfigure stdout) lives in skill harness-authoring "Running scripts on this Windows checkout" — don't duplicate it. Do NOT reach for a global PYTHONUTF8 env override: it masks a non-robust committed script that then breaks in CI / another env, defeating that robustness. (session 908de0ac, 2026-06-21: inline ast.parse(open(...)) + a later command that dropped the flag crashed cp1252 3× during an otherwise-clean auto-healer build/verify.)

To confirm a test is import-safe for no-pip CI, do NOT grep '^(import|from)': that anchor misses third-party imports indented inside try/except ImportError skip-guards (and lazy in-function imports) — a FALSE "stdlib-only" all-clear. Match leading whitespace (^\s*(import|from)) or, better, PROVE it: run the test under bare python3 with the suspect package un-importable (a sys.modules blocker / pip-less env); a green run is proof, a source regex is a guess. (session 37226faa, 2026-06-23: an ^import- anchored scan twice declared 3 textual-importing mission_control tests "stdlib-only"; only the harness-auditor, which ran them under a textual blocker, caught it.)

Property tests bind green to intent (the one new procedure)

An example test can certify your own assumption; a property derived from the spec's INTENT, before the code, is tied to something you did not author — so green proves intent, not just example-pass. The authoring bar + worked examples live in references/property-tests.md. The cartograph evals' "contracts not counts" check scripts are the in-repo precedent.

Fan-out refactors with a static-equivalence contract

When N independent files need the SAME semantics-preserving refactor (a codemod, a rename, composing a shared layer), dispatch one subagent per file IN PARALLEL — but replace post-hoc verification (the orchestrator diffing each result) with a correctness-BY-CONSTRUCTION contract each agent must satisfy and PROVE:

1. Hand it the canonical mapping (old value → new symbol) as an explicit table.
2. Rule: apply a swap ONLY where EVERY property the element sets EXACTLY equals the target's; otherwise leave it local. "When in doubt, leave local." Forbid swaps that ADD or remove a property — that changes computed output (not semantics-preserving).
3. Require a per-swap proof line in the report (old == new: YES) + a mechanical gate (lint / type-check / suite) that must PASS. The proof obligation is what makes parallel fan-out safe WITHOUT a human diffing each result: the orchestrator reconciles only the REPORTED exceptions, then runs the full suite ONCE (the cold green of phase 4-5). (session 1a5cff26, 2026-06-22: 7 surface files retrofitted to compose a shared CSS component layer — 7/7 returned clean, agents even refused swaps that would ADD a line-height the element lacked.)

Relationships (one name per concept — never fork)

• venture-build is the multi-session, board-managed, scaffold+ledger SUPERSET for whole products; it CITES this skill for the per-feature inner loop and keeps its own grading-independence + validate-live gates. This skill is the generic core, not a competitor; venture-build phase 4 keeps tests-as-you-go for MVP pace, while this loop tightens to tests-RED-first for an individual feature.
• Specs: the binding format now EXISTS (proposal 2026-06-21-spec-driven-dev.md; the cartograph spec layer — spec: frontmatter resolved by extract.py --query governed-by/traces, gated by --check). Phase-1 READS criteria from a governing spec's requirements:; phase-6 writes the regression into its verified_by:. This skill CONSUMES that format — it never defines or forks it (routing-learnings: strengthen the near-match). With no governing spec, write the criteria inline as before.
• cartograph oracle (cartograph/extract.py --context/--query): query it for "what depends on this / blast radius" instead of narrating relationships.
• Strengthen THIS skill for any loop refinement; never spawn a second methodology skill (routing-learnings: strengthen a near-match). A mechanical always/never → hook; an isolated role → agent — route per the tree, don't bolt it on here.