fix(generate): route vision by model tier

docs/configuration.md

@@ -113,6 +113,11 @@ Each entry under `models:`:
 | `thinking` | the levels the model really offers (see below) |
 | `image` | omitted for image-capable models, which is most of them. `init` writes `image: false` only for a model omp reports as text-only, and the `vision` role then avoids it |
 
+The `vision` lead follows the model dial: `fast`, `normal`, and `smart` select
+tiers 1, 2, and 3 respectively. Mixed routing keeps GPT for fast and normal,
+then prefers Claude's tier-3 model for smart, with the GPT tier-3 model in its
+fallback chain. Any text-only rung is skipped.
+
 The thinking scale is `minimal · low · medium · high · xhigh · max`. Write
 `low→max` for a contiguous run, or a comma list when the model skips a level:
 claude-opus-4-6 offers `low,medium,high,max` but not `xhigh`, and a range there

generate.go

@@ -307,10 +307,17 @@ func (c *catalog) buildChain(lead string, isPure bool) []string {
 	return dedup([]string{sib, cr, c.sibDown(cr)}, lead)
 }
 
-// visionLead is the cheapest rung on a pool that accepts image input. The
-// codex spark variants are text-only, so the cheapest rung is not always it.
-func (c *catalog) visionLead(pool string) string {
-	for t := 1; t <= 3; t++ {
+// visionLead returns the requested capability rung when it accepts images.
+// If that rung is text-only, prefer a more capable rung before stepping down;
+// the model dial must still influence vision without ever routing images to a
+// model that cannot consume them.
+func (c *catalog) visionLead(pool string, tier int) string {
+	for t := tier; t <= 3; t++ {
+		if k := c.ladder[pool][t]; k != "" && c.models[k].multimodal() {
+			return k
+		}
+	}
+	for t := tier - 1; t >= 1; t-- {
 		if k := c.ladder[pool][t]; k != "" && c.models[k].multimodal() {
 			return k
 		}
@@ -438,10 +445,15 @@ func (c *catalog) genCombo(lane, mtier, thinking string, spark, fable, fableMain
 		if r == "vision" {
 			// omp falls back @vision → @default → active model when it needs an
 			// image described, and describeForTextModels is on by default — so
-			// this rung must be a model that actually accepts images.
-			lead := c.visionLead(p)
+			// this rung must be a model that actually accepts images. Vision
+			// follows the model tier; mixed smart prefers Claude's smart rung.
+			vp := p
+			if lane == "mixed" && mtier == "smart" {
+				vp = "A"
+			}
+			lead := c.visionLead(vp, base)
 			if lead == "" && !isPure {
-				lead = c.visionLead(otherPool(p))
+				lead = c.visionLead(otherPool(vp), base)
 			}
 			if lead == "" {
 				out[r] = roleRoute{}

generate_test.go

@@ -157,7 +157,7 @@ const goldenMixedSmart = `mixed_smart_medium_sp_fa  mixed · smart · medium ·
   ● scout      gpt-5.6-terra:medium     → gpt-5.6-luna:medium
   ● sonic      gpt-5.6-terra:medium     → gpt-5.6-luna:medium
     advisor    claude-sonnet-5:high     → claude-haiku-4-5:low → gpt-5.6-terra:low → gpt-5.6-luna:low
-    vision     gpt-5.6-luna:low         → claude-haiku-4-5:low
+    vision     claude-opus-5:low        → claude-sonnet-5:low → gpt-5.6-sol:low → gpt-5.6-terra:low
     smol       gpt-5.6-terra:low
     tiny       gpt-5.3-codex-spark:low  → gpt-5.6-terra:low
     commit     gpt-5.3-codex-spark:low  → gpt-5.6-luna:low
@@ -175,7 +175,7 @@ const goldenClaudeMax = `claude-only_normal_max_nosp_famain  claude-only · norm
   ● scout      claude-sonnet-5:max      → claude-haiku-4-5:xhigh
   ● sonic      claude-sonnet-5:max      → claude-haiku-4-5:xhigh
     advisor    claude-haiku-4-5:xhigh
-    vision     claude-haiku-4-5:xhigh
+    vision     claude-sonnet-5:max      → claude-haiku-4-5:xhigh
     smol       claude-sonnet-5:max
     tiny       claude-haiku-4-5:xhigh
     commit     claude-haiku-4-5:xhigh
@@ -197,7 +197,7 @@ const goldenClaudeSmart = `claude-only_smart_medium_nosp_nofa  claude-only · sm
   ● scout      claude-sonnet-5:medium   → claude-haiku-4-5:medium
   ● sonic      claude-sonnet-5:medium   → claude-haiku-4-5:medium
     advisor    claude-sonnet-5:high     → claude-haiku-4-5:low
-    vision     claude-haiku-4-5:low
+    vision     claude-opus-5:low        → claude-sonnet-5:low → claude-haiku-4-5:low
     smol       claude-sonnet-5:low
     tiny       claude-sonnet-5:low
     commit     claude-haiku-4-5:minimal
@@ -370,8 +370,8 @@ func TestVisionSkipsTextOnlyModels(t *testing.T) {
 	if err != nil {
 		t.Fatalf("loadCatalog: %v", err)
 	}
-	if lead := c.visionLead("O"); lead == "" || c.models[lead].ID != "gpt-5.6-terra" {
-		t.Errorf("visionLead(O) = %q, want the cheapest image-capable rung (terra)", lead)
+	if lead := c.visionLead("O", 1); lead == "" || c.models[lead].ID != "gpt-5.6-terra" {
+		t.Errorf("visionLead(O, 1) = %q, want the next image-capable rung (terra)", lead)
 	}
 	block := c.renderCombo("gpt-only", "fast", "medium", false, false, false)
 	for _, l := range strings.Split(block, "\n") {
@@ -381,6 +381,30 @@ func TestVisionSkipsTextOnlyModels(t *testing.T) {
 	}
 }
 
+func TestVisionFollowsModelTier(t *testing.T) {
+	c := fixtureCatalog(t)
+	for _, tc := range []struct {
+		lane, tier, want string
+	}{
+		{"gpt-only", "fast", "gpt-5.6-luna"},
+		{"gpt-only", "normal", "gpt-5.6-terra"},
+		{"gpt-only", "smart", "gpt-5.6-sol"},
+		{"claude-only", "fast", "claude-haiku-4-5"},
+		{"claude-only", "normal", "claude-sonnet-5"},
+		{"claude-only", "smart", "claude-opus-5"},
+		{"mixed", "fast", "gpt-5.6-luna"},
+		{"mixed", "normal", "gpt-5.6-terra"},
+		{"mixed", "smart", "claude-opus-5"},
+	} {
+		t.Run(tc.lane+"/"+tc.tier, func(t *testing.T) {
+			route := c.genCombo(tc.lane, tc.tier, "medium", false, false, false)["vision"]
+			if got := c.models[route.lead].ID; got != tc.want {
+				t.Errorf("vision lead = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
 func TestCatalogWithoutOptionalTiers(t *testing.T) {
 	trimmed := ""
 	skip := false