fix: address swarm review of consensus consolidation (PR #17)

From PR #17's own adversarial review (now running on the Phase-1 image — note
the much cleaner, less-fragmented findings). Graded in gadfly-reports.

- Never lose output (advisory invariant): run.sh writes a stub findings file
  when a model fails/skips under consolidation, so a failed model still shows
  (as failed) and an all-models-fail run still posts a comment.
- Errored models excluded from the agreement denominator (modelFindings.Errored
  + allErrored); shown folded as "reviewer failed", not counted as clean.
- Sliding cluster window: span [line,maxLine] widened by tolerance on both
  edges, so chains of nearby findings merge instead of splitting (fixes
  agreement under-counting). Clustering is now per-file (no global O(n²) scan).
- Lone-finding headline threshold raised high -> critical (matches the docs);
  only consensus or a lone critical earns the headline, the rest fold.
- findings_file_for appends a cksum so foo:bar vs foo/bar can't collide.
- mdCell escapes the location cell + neutralizes backticks (table-injection);
  "No material issues" no longer shown when folded findings exist.
- Removed dead cluster.detail; named findingRef type; single partition/agreed
  pass; writeFindingsOut MkdirAll; captureStdout defer-restore + close.

Tests added: sliding-window chain merge, errored-denominator exclusion, lone
HIGH folds. gofmt/vet/bash -n clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cmd/gadfly/consensus.go

@@ -38,6 +38,7 @@ type modelFindings struct {
 	Model    string       `json:"model"`
 	Provider string       `json:"provider"`
 	Verdict  string       `json:"verdict"`  // worst lens verdict, as a label
+	Errored  bool         `json:"errored"`  // the model produced no usable review (every lens failed, or the run crashed)
 	Markdown string       `json:"markdown"` // full rendered per-model review (findings block already stripped)
 	Findings []outFinding `json:"findings"`
 }
@@ -86,6 +87,7 @@ func writeFindingsOut(results []specialistResult) {
 		Model:    strings.TrimSpace(os.Getenv("GADFLY_MODEL")),
 		Provider: modelProvider(),
 		Verdict:  worstVerdict(results).label(),
+		Errored:  allErrored(results),
 		Markdown: renderConsolidated(results),
 	}
 	for _, r := range results {
@@ -106,11 +108,32 @@ func writeFindingsOut(results []specialistResult) {
 		fmt.Fprintln(os.Stderr, "gadfly: marshal findings out:", err)
 		return
 	}
+	// Defensive: make sure the parent dir exists (entrypoint creates it, but a
+	// missing dir would otherwise silently drop this model from the consensus).
+	if dir := filepath.Dir(path); dir != "" {
+		_ = os.MkdirAll(dir, 0o755)
+	}
 	if err := os.WriteFile(path, data, 0o644); err != nil {
 		fmt.Fprintln(os.Stderr, "gadfly: write findings out:", err)
 	}
 }
 
+// allErrored reports whether every lens of a review failed (so the model
+// produced no usable findings). Such a model is recorded but excluded from the
+// consensus agreement denominator — counting it would dilute every ratio with a
+// model that never actually reviewed.
+func allErrored(results []specialistResult) bool {
+	if len(results) == 0 {
+		return true
+	}
+	for _, r := range results {
+		if !r.errored {
+			return false
+		}
+	}
+	return true
+}
+
 // runConsolidate is the consolidation entry point (GADFLY_CONSOLIDATE_DIR set):
 // read every per-model artifact in the directory, render the consensus comment
 // to stdout. Errors are fatal to THIS process only — entrypoint.sh treats a
@@ -155,26 +178,45 @@ func runConsolidate() error {
 }
 
 // cluster is a group of findings (across models) judged to be the same issue:
-// same file, lines within lineTolerance of each other.
+// same file, lines within lineTolerance of the cluster's current span. The span
+// [line,maxLine] slides as members join, so a chain of nearby findings merges
+// instead of splitting once it drifts past the first line.
 type cluster struct {
 	file     string
 	line     int // representative (smallest) line
+	maxLine  int // largest line in the cluster — the span's upper edge
 	severity string
 	title    string
-	detail   string
 	models   map[string]bool
 	lenses   map[string]bool
 }
 
-// lineTolerance: findings in the same file within this many lines of each other
-// are treated as the same issue (models often cite a line or two apart).
+// findingRef is one model's finding (carrying which model reported it), used
+// while grouping findings into clusters.
+type findingRef struct {
+	f     outFinding
+	model string
+}
+
+// lineTolerance: a finding in the same file within this many lines of a
+// cluster's current span is treated as the same issue (models often cite a line
+// or two apart).
 const lineTolerance = 3
 
 // renderConsensus builds the single consolidated comment body from every model's
 // findings. It does NOT emit the marker or advisory footer — entrypoint.sh wraps
 // it (mirroring run.sh's per-model framing).
 func renderConsensus(models []modelFindings) string {
-	total := len(models)
+	// effective = models that actually produced a review. Errored models are
+	// shown (folded, below) but excluded from the agreement denominator so a
+	// failed model doesn't dilute every ratio.
+	effective := 0
+	for _, m := range models {
+		if !m.Errored {
+			effective++
+		}
+	}
+	errored := len(models) - effective
 	clusters := clusterFindings(models)
 
 	worst := verdictClean
@@ -184,11 +226,16 @@ func renderConsensus(models []modelFindings) string {
 		}
 	}
 
-	// Partition: "headline" findings (multi-model agreement, OR a high/critical
-	// even from one model) vs folded "single-model" lower-severity noise.
+	// Partition in one pass: "headline" findings (multi-model agreement, OR a
+	// lone CRITICAL) vs folded "single-model" lower-confidence findings. Also
+	// count multi-model agreements for the summary line.
 	var headline, folded []cluster
+	agreed := 0
 	for _, c := range clusters {
-		if len(c.models) >= 2 || sevRank(c.severity) >= sevRank("high") {
+		if len(c.models) >= 2 {
+			agreed++
+		}
+		if len(c.models) >= 2 || sevRank(c.severity) >= sevRank("critical") {
 			headline = append(headline, c)
 		} else {
 			folded = append(folded, c)
@@ -196,13 +243,11 @@ func renderConsensus(models []modelFindings) string {
 	}
 
 	var b strings.Builder
-	fmt.Fprintf(&b, "## 🪰 Gadfly review — consensus across %d model%s\n\n", total, plural(total))
-	agreed := 0
-	for _, c := range clusters {
-		if len(c.models) >= 2 {
-			agreed++
-		}
+	fmt.Fprintf(&b, "## 🪰 Gadfly review — consensus across %d model%s", effective, plural(effective))
+	if errored > 0 {
+		fmt.Fprintf(&b, " (%d failed)", errored)
 	}
+	b.WriteString("\n\n")
 	fmt.Fprintf(&b, "**Verdict: %s** · %d finding%s (%d with multi-model agreement)\n",
 		worst.label(), len(clusters), plural(len(clusters)), agreed)
 
@@ -210,12 +255,14 @@ func renderConsensus(models []modelFindings) string {
 		b.WriteString("\n| | Finding | Where | Models | Lens |\n|--|--|--|--|--|\n")
 		for _, c := range headline {
 			fmt.Fprintf(&b, "| %s | %s | `%s` | %d/%d | %s |\n",
-				sevIcon(c.severity), mdCell(c.title), location(c.file, c.line),
-				len(c.models), total, mdCell(lensList(c.lenses)))
+				sevIcon(c.severity), mdCell(c.title), mdCell(location(c.file, c.line)),
+				len(c.models), effective, mdCell(lensList(c.lenses)))
 		}
-	} else {
+	} else if len(clusters) == 0 {
 		b.WriteString("\nNo material issues found by consensus.\n")
 	}
+	// else: only single-model findings — they're shown folded below, so don't
+	// claim "no material issues" (there are some, just none with consensus).
 
 	if len(folded) > 0 {
 		fmt.Fprintf(&b, "\n<details><summary>%d single-model finding%s (lower confidence)</summary>\n\n",
@@ -223,7 +270,7 @@ func renderConsensus(models []modelFindings) string {
 		b.WriteString("| | Finding | Where | Model | Lens |\n|--|--|--|--|--|\n")
 		for _, c := range folded {
 			fmt.Fprintf(&b, "| %s | %s | `%s` | %s | %s |\n",
-				sevIcon(c.severity), mdCell(c.title), location(c.file, c.line),
+				sevIcon(c.severity), mdCell(c.title), mdCell(location(c.file, c.line)),
 				mdCell(oneModel(c.models)), mdCell(lensList(c.lenses)))
 		}
 		b.WriteString("\n</details>\n")
@@ -236,8 +283,12 @@ func renderConsensus(models []modelFindings) string {
 		if body == "" {
 			body = "_(no output)_"
 		}
+		verdict := m.Verdict
+		if m.Errored {
+			verdict = "⚠️ reviewer failed"
+		}
 		fmt.Fprintf(&b, "\n<details><summary><b>%s</b> (%s) — %s</summary>\n\n%s\n\n</details>\n",
-			mdCell(m.Model), mdCell(m.Provider), m.Verdict, body)
+			mdCell(m.Model), mdCell(m.Provider), verdict, body)
 	}
 	b.WriteString("\n</details>")
 	return b.String()
@@ -247,30 +298,29 @@ func renderConsensus(models []modelFindings) string {
 // sorted by agreement (desc), then severity (desc), then location.
 func clusterFindings(models []modelFindings) []cluster {
 	// Group by file, then greedily merge by line proximity.
-	byFile := map[string][]struct {
-		f     outFinding
-		model string
-	}{}
+	byFile := map[string][]findingRef{}
 	for _, m := range models {
 		for _, f := range m.Findings {
 			if strings.TrimSpace(f.File) == "" {
 				continue
 			}
-			byFile[f.File] = append(byFile[f.File], struct {
-				f     outFinding
-				model string
-			}{f, m.Model})
+			byFile[f.File] = append(byFile[f.File], findingRef{f, m.Model})
 		}
 	}
 
 	var clusters []cluster
 	for file, items := range byFile {
 		sort.SliceStable(items, func(i, j int) bool { return items[i].f.Line < items[j].f.Line })
+		// Cluster within THIS file only (clusters never span files), so the inner
+		// scan is over same-file clusters, not every cluster seen so far.
+		var fileClusters []cluster
 		for _, it := range items {
 			placed := false
-			for ci := range clusters {
-				c := &clusters[ci]
-				if c.file == file && absInt(c.line-it.f.Line) <= lineTolerance {
+			for ci := range fileClusters {
+				c := &fileClusters[ci]
+				// Join if the line falls within the cluster's span, widened by the
+				// tolerance on both edges — so the window slides as the span grows.
+				if it.f.Line >= c.line-lineTolerance && it.f.Line <= c.maxLine+lineTolerance {
 					mergeIntoCluster(c, it.f, it.model)
 					placed = true
 					break
@@ -280,16 +330,17 @@ func clusterFindings(models []modelFindings) []cluster {
 				c := cluster{
 					file:     file,
 					line:     it.f.Line,
+					maxLine:  it.f.Line,
 					severity: it.f.Severity,
 					title:    it.f.Title,
-					detail:   it.f.Detail,
 					models:   map[string]bool{},
 					lenses:   map[string]bool{},
 				}
 				mergeIntoCluster(&c, it.f, it.model)
-				clusters = append(clusters, c)
+				fileClusters = append(fileClusters, c)
 			}
 		}
+		clusters = append(clusters, fileClusters...)
 	}
 
 	sort.SliceStable(clusters, func(i, j int) bool {
@@ -308,7 +359,7 @@ func clusterFindings(models []modelFindings) []cluster {
 }
 
 // mergeIntoCluster folds one finding into a cluster: union the model/lens sets,
-// keep the smallest line, and keep the highest-severity report's title/detail.
+// widen the [line,maxLine] span, and keep the highest-severity report's title.
 func mergeIntoCluster(c *cluster, f outFinding, model string) {
 	if model != "" {
 		c.models[model] = true
@@ -319,14 +370,14 @@ func mergeIntoCluster(c *cluster, f outFinding, model string) {
 	if f.Line > 0 && (c.line == 0 || f.Line < c.line) {
 		c.line = f.Line
 	}
+	if f.Line > c.maxLine {
+		c.maxLine = f.Line
+	}
 	if sevRank(f.Severity) > sevRank(c.severity) {
 		c.severity = f.Severity
 		if strings.TrimSpace(f.Title) != "" {
 			c.title = f.Title
 		}
-		if strings.TrimSpace(f.Detail) != "" {
-			c.detail = f.Detail
-		}
 	}
 }
 
@@ -385,11 +436,15 @@ func oneModel(models map[string]bool) string {
 	return ""
 }
 
-// mdCell makes a string safe for a one-line markdown table cell: escape pipes,
-// collapse newlines.
+// mdCell makes a string safe for a one-line markdown table cell: collapse
+// newlines, escape pipes (which delimit columns), and neutralize backticks
+// (a stray one would break an inline-code span — a backslash can't escape it
+// inside code, so replace with an apostrophe). Inputs are model-influenced, so
+// this keeps a malformed file path or title from breaking the table.
 func mdCell(s string) string {
 	s = strings.ReplaceAll(s, "\n", " ")
 	s = strings.ReplaceAll(s, "|", "\\|")
+	s = strings.ReplaceAll(s, "`", "'")
 	return strings.TrimSpace(s)
 }
 
@@ -399,10 +454,3 @@ func plural(n int) string {
 	}
 	return "s"
 }
-
-func absInt(n int) int {
-	if n < 0 {
-		return -n
-	}
-	return n
-}

cmd/gadfly/consensus_test.go

@@ -88,6 +88,61 @@ func TestRenderConsensusHighSeverityLoneFindingStaysHeadline(t *testing.T) {
 	}
 }
 
+func TestClusterSlidingWindowMergesChain(t *testing.T) {
+	// Findings at 10, 13, 16 (each 3 apart) from three models must merge into ONE
+	// cluster — the window slides with the span instead of anchoring at line 10.
+	models := []modelFindings{
+		{Model: "m1", Findings: []outFinding{{Lens: "x", File: "a.go", Line: 10, Severity: "medium", Title: "t"}}},
+		{Model: "m2", Findings: []outFinding{{Lens: "x", File: "a.go", Line: 13, Severity: "medium", Title: "t"}}},
+		{Model: "m3", Findings: []outFinding{{Lens: "x", File: "a.go", Line: 16, Severity: "medium", Title: "t"}}},
+	}
+	clusters := clusterFindings(models)
+	if len(clusters) != 1 {
+		t.Fatalf("chain 10/13/16 should merge into 1 cluster, got %d", len(clusters))
+	}
+	if len(clusters[0].models) != 3 {
+		t.Errorf("want 3 models in the merged cluster, got %d", len(clusters[0].models))
+	}
+}
+
+func TestRenderConsensusExcludesErroredFromDenominator(t *testing.T) {
+	models := []modelFindings{
+		{Model: "m1", Verdict: "Minor issues", Markdown: "a", Findings: []outFinding{
+			{Lens: "security", File: "a.go", Line: 9, Severity: "medium", Title: "leak"}}},
+		{Model: "m2", Verdict: "Minor issues", Markdown: "b", Findings: []outFinding{
+			{Lens: "security", File: "a.go", Line: 9, Severity: "medium", Title: "leak"}}},
+		{Model: "broken", Verdict: "reviewer failed", Errored: true, Markdown: "boom"},
+	}
+	out := renderConsensus(models)
+	// Denominator is the 2 effective models, not 3; the failure is noted.
+	if !strings.Contains(out, "2/2") {
+		t.Errorf("errored model must be excluded from the denominator (want 2/2):\n%s", out)
+	}
+	if !strings.Contains(out, "1 failed") {
+		t.Errorf("expected a '1 failed' note:\n%s", out)
+	}
+	if !strings.Contains(out, "reviewer failed") {
+		t.Errorf("errored model should still appear (folded) as failed:\n%s", out)
+	}
+}
+
+func TestRenderConsensusLoneHighFolds(t *testing.T) {
+	// A single-model HIGH (not critical) folds — only consensus or a lone CRITICAL
+	// earns the headline, so a lone Blocking-lens finding doesn't reintroduce noise.
+	models := []modelFindings{
+		{Model: "solo", Verdict: "Blocking issues found", Markdown: "x", Findings: []outFinding{
+			{Lens: "security", File: "a.go", Line: 1, Severity: "high", Title: "maybe-bug"}}},
+	}
+	out := renderConsensus(models)
+	head := out
+	if i := strings.Index(out, "single-model finding"); i >= 0 {
+		head = out[:i]
+	}
+	if strings.Contains(head, "maybe-bug") {
+		t.Errorf("a lone HIGH should fold, not headline:\n%s", out)
+	}
+}
+
 func TestWriteAndConsolidateRoundTrip(t *testing.T) {
 	dir := t.TempDir()
 
@@ -139,6 +194,7 @@ func captureStdout(t *testing.T, fn func()) string {
 		t.Fatal(err)
 	}
 	os.Stdout = w
+	defer func() { os.Stdout = orig }() // restore even if fn panics
 	done := make(chan string)
 	go func() {
 		var sb strings.Builder
@@ -152,10 +208,10 @@ func captureStdout(t *testing.T, fn func()) string {
 				break
 			}
 		}
+		r.Close()
 		done <- sb.String()
 	}()
 	fn()
 	w.Close()
-	os.Stdout = orig
 	return <-done
 }

entrypoint.sh

@@ -235,7 +235,16 @@ case "${GADFLY_CONSOLIDATE:-auto}" in
   0) CONSOLIDATE=0 ;;
   *) [ "${#MODEL_LIST[@]}" -ge 2 ] && CONSOLIDATE=1 ;;
 esac
-findings_file_for() { echo "${FINDINGS_DIR}/$(echo "$1" | tr -c '[:alnum:]._-' '_').json"; }
+# A model spec can contain '/' and ':' (e.g. claude-code/opus, qwen3:14b), so
+# sanitize to a flat filename — but append a checksum of the raw spec so two
+# specs that sanitize the same (foo:bar vs foo/bar -> foo_bar) don't collide onto
+# one file and silently drop a model from the consensus.
+findings_file_for() {
+  local safe sum
+  safe="$(echo "$1" | tr -c '[:alnum:]._-' '_')"
+  sum="$(printf '%s' "$1" | cksum | cut -d' ' -f1)"
+  echo "${FINDINGS_DIR}/${safe}-${sum}.json"
+}
 if [ "$CONSOLIDATE" = "1" ]; then
   rm -rf "$FINDINGS_DIR"; mkdir -p "$FINDINGS_DIR"
   log "consolidation ON: ${#MODEL_LIST[@]} models -> one consensus comment"

scripts/run.sh

@@ -214,6 +214,16 @@ esac
 # --- assemble + post final comment (with run time) --------------------------
 ELAPSED="$(( $(date +%s) - START_TS ))"
 DUR="$(fmt_duration "$ELAPSED")"
+
+# Consolidating: the binary writes its findings file on success. If it failed or
+# was skipped (no file, or an empty one), write a stub so this model still shows
+# up in the consensus (as failed) and an all-models-fail run still posts a
+# comment — never silently drop a model or the whole review.
+if [ "$CONSOLIDATE" = "1" ] && [ -n "${GADFLY_FINDINGS_OUT:-}" ] && [ ! -s "${GADFLY_FINDINGS_OUT}" ]; then
+  jq -n --arg model "$MODEL" --arg provider "$MODEL_PROVIDER" --arg md "$REVIEW" \
+    '{model:$model, provider:$provider, verdict:"reviewer failed", errored:true, markdown:$md, findings:[]}' \
+    > "${GADFLY_FINDINGS_OUT}" 2>/dev/null || true
+fi
 # When consolidating, the binary has written this model's findings to
 # GADFLY_FINDINGS_OUT; the consensus comment is posted by entrypoint.sh after the
 # whole swarm finishes, so this model posts no comment of its own.