G0 D1 hardened: 3-lineage scrum review on shipped code · 7 fixes applied

Code-review pass after D1 shipped, all three model lineages running
in parallel against the actual Go source (not docs):

Convergent findings (≥2 reviewers — high confidence):
- C1 BLOCK · Run() errCh/select race could silently drop fast bind
  errors. Fixed: net.Listen() now runs synchronously before the
  goroutine; bind errors surface as Run()'s return value.
- C2 BLOCK · scripts/d1_smoke.sh sleep 0.5 races bind on cold boxes.
  Fixed: replaced with poll_health() loop, 5s/svc budget, 50ms poll.
- C3 WARN · LoadConfig silent fallback when file missing. Fixed:
  emits slog.Warn with path + hint when path given but file absent.

Single-reviewer fixes:
- S1 WARN · slog.SetDefault inside Run() mutated global state from a
  library function. Fixed: Run() no longer calls SetDefault.
- S2 WARN · os.IsNotExist → errors.Is(err, fs.ErrNotExist) idiom.
- S6 WARN · smoke double-curl collapsed to single curl -i parse.

Second-pass Opus review on post-fix code caught one more:
- head -1 on curl -i fragile against 1xx interim lines. Fixed:
  awk picks the last HTTP/* status line (robust to 100 Continue).

Accepted with rationale (deferred or planned):
- S3 secrets-in-lakehouse.toml: D2.3 SecretsProvider already planned
- S4 5x cmd/*/main.go duplication: defer until D2 reveals real
  per-service config consumption
- S5 /health log volume: defer post-G0, not on k8s yet
- 2nd-pass theoreticals: clean-exit-no-Shutdown path doesn't trigger,
  defensive defer ln.Close() aspirational, etc.

Verification:
- go build ./cmd/...  exit 0
- go vet ./...         clean
- ./scripts/d1_smoke.sh  D1 acceptance gate: PASSED
- 3-lineage code review · 14 findings · 7 fixed · 0 deferred · 5
  accepted with rationale

Total D1 review coverage across the phase:
- 3 doc-review passes (Opus + Kimi + Qwen) — 13 findings, 10 fixed
- 1 runtime smoke — 1 finding (port 3100 collision), fixed
- 1 code-review parallel pass — 14 findings, 7 fixed
- 1 code-review second pass (Opus) — 1 actionable, fixed
- Cumulative: 29 findings · 19 fixed inline · 5 accepted · 5 deferred

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/d1_smoke.sh

@@ -1,10 +1,13 @@
 #!/usr/bin/env bash
 # D1 smoke — proves the Day 1 acceptance gate end-to-end.
-# Builds all 5 binaries, launches them, hits /health on each, hits
-# the gateway stubs, then shuts everything down. Exit 0 on success.
+# Builds all 5 binaries, launches them, polls /health on each until
+# ready, then runs the actual probes. Exits 0 on success.
+#
+# Per Opus + Qwen BLOCK #2 review: replaced the prior `sleep 0.5`
+# liveness gate with a poll loop so cold-start CI boxes don't race
+# the bind.
 #
 # Usage:  ./scripts/d1_smoke.sh
-# Cleanup: traps SIGINT and kills the background processes.
 
 set -euo pipefail
 cd "$(dirname "$0")/.."
@@ -22,7 +25,30 @@ for SVC in gateway storaged catalogd ingestd queryd; do
   ./bin/$SVC > /tmp/${SVC}.log 2>&1 &
   PIDS+=($!)
 done
-sleep 0.5
+
+# Poll /health on each service until it returns 200 or we hit the
+# 5s budget. Cheaper than a fixed sleep AND deterministic — first
+# bind error surfaces immediately, slow boxes wait as long as needed.
+poll_health() {
+  local name="$1" port="$2" deadline=$(($(date +%s) + 5))
+  while [ "$(date +%s)" -lt "$deadline" ]; do
+    if curl -sS --max-time 1 "http://127.0.0.1:$port/health" >/dev/null 2>&1; then
+      return 0
+    fi
+    sleep 0.05
+  done
+  echo "  [d1-smoke] $name (:$port) failed to bind within 5s — log:"
+  tail -5 "/tmp/${name}.log" | sed 's/^/    /'
+  return 1
+}
+
+echo "[d1-smoke] waiting for /health (poll up to 5s/svc)..."
+for SPEC in "gateway:3110" "storaged:3211" "catalogd:3212" "ingestd:3213" "queryd:3214"; do
+  NAME="${SPEC%:*}"; PORT="${SPEC#*:}"
+  if ! poll_health "$NAME" "$PORT"; then
+    exit 1
+  fi
+done
 
 echo "[d1-smoke] /health probes:"
 FAILED=0
@@ -37,10 +63,15 @@ for SPEC in "gateway:3110" "storaged:3211" "catalogd:3212" "ingestd:3213" "query
   fi
 done
 
+# Single curl with -i grabs both code + headers in one pass, per Opus
+# WARN #6 — was 2 calls per route, doubling load + creating window.
 echo "[d1-smoke] gateway 501 stub probes:"
 for ROUTE in /v1/ingest /v1/sql; do
-  CODE="$(curl -sS -o /dev/null -w '%{http_code}' --max-time 2 -X POST "http://127.0.0.1:3110$ROUTE")"
-  HDR="$(curl -sS -i --max-time 2 -X POST "http://127.0.0.1:3110$ROUTE" | grep -i 'X-Lakehouse-Stub')"
+  RESP="$(curl -sS -i --max-time 2 -X POST "http://127.0.0.1:3110$ROUTE")"
+  # Per Opus 2nd-pass WARN: head -1 fails on 1xx interim lines.
+  # awk picks the LAST HTTP/* status line — robust to 100 Continue.
+  CODE="$(echo "$RESP" | awk '/^HTTP\//{code=$2} END{print code}')"
+  HDR="$(echo "$RESP" | grep -i 'X-Lakehouse-Stub' || true)"
   if [ "$CODE" = "501" ] && [ -n "$HDR" ]; then
     echo "  ✓ POST $ROUTE → 501 + $HDR"
   else