diff --git a/src/llm/anthropic/params.rs b/src/llm/anthropic/params.rs
index 11dcda8ef..103dff9de 100644
--- a/src/llm/anthropic/params.rs
+++ b/src/llm/anthropic/params.rs
@@ -19,12 +19,25 @@ pub struct AnthropicRequest {
     pub original_tools: Vec<(String, String)>,
 }
 
-/// Adaptive thinking is only available on 4.6-generation models.
+/// Adaptive thinking is available on every 4.6-generation-and-later model —
+/// the API rejects the old `{type: "enabled", budget_tokens: N}` shape on
+/// these and only accepts `{type: "adaptive"}` (or the field omitted, which
+/// silently runs without thinking). Checked by family/prefix rather than a
+/// single generation string so onboarding a new model is one line here, not
+/// a parallel gating rewrite. Was previously scoped to literal "4-6"/"4.6"
+/// only, which silently missed Opus 4.7, Opus 4.8, and Opus 5 — those
+/// workers ran with no `thinking` param at all until this fix (2026-07-29).
 fn supports_adaptive_thinking(model_id: &str) -> bool {
-    model_id.contains("opus-4-6")
-        || model_id.contains("opus-4.6")
-        || model_id.contains("sonnet-4-6")
-        || model_id.contains("sonnet-4.6")
+    const ADAPTIVE_ONLY_FRAGMENTS: &[&str] = &[
+        "opus-4-6", "opus-4.6",
+        "opus-4-7", "opus-4.7",
+        "opus-4-8", "opus-4.8",
+        "opus-5",
+        "sonnet-4-6", "sonnet-4.6",
+        "sonnet-5",
+        "fable-5", "mythos-5",
+    ];
+    ADAPTIVE_ONLY_FRAGMENTS.iter().any(|f| model_id.contains(*f))
 }
 
 fn is_opus(model_id: &str) -> bool {
@@ -218,4 +231,18 @@ mod tests {
         assert!(!supports_adaptive_thinking("claude-opus-4-0"));
         assert!(!supports_adaptive_thinking("gpt-4o"));
     }
+
+    #[test]
+    fn adaptive_thinking_detected_for_opus_5_and_the_rest_of_the_4_6plus_family() {
+        // Regression test: the original gate only matched literal "4-6",
+        // silently missing every later adaptive-only model — Opus 4.7, Opus
+        // 4.8, and Opus 5 (the current worker default) all ran with no
+        // `thinking` param at all before this fix.
+        assert!(supports_adaptive_thinking("anthropic/claude-opus-5"));
+        assert!(supports_adaptive_thinking("claude-opus-4-7"));
+        assert!(supports_adaptive_thinking("claude-opus-4-8"));
+        assert!(supports_adaptive_thinking("anthropic/claude-sonnet-5"));
+        assert!(supports_adaptive_thinking("claude-fable-5"));
+        assert!(supports_adaptive_thinking("claude-mythos-5"));
+    }
 }
diff --git a/src/llm/pricing.rs b/src/llm/pricing.rs
index c27384d34..7a5f754cc 100644
--- a/src/llm/pricing.rs
+++ b/src/llm/pricing.rs
@@ -31,7 +31,8 @@ fn lookup_pricing(model_name: &str) -> ModelPricing {
     // ORDER IS LOAD-BEARING for the Anthropic arms: specific prefixes
     // (claude-opus-4-8) must precede their generic parent (claude-opus-4) —
     // the first matching arm wins.
-    // Prices verified 2026-07-03 against platform.claude.com pricing docs.
+    // Prices verified 2026-07-29 against platform.claude.com pricing docs
+    // (Claude Opus 5 confirmed $5/$25 — same tier as Opus 4.5+).
     match model {
         m if m.starts_with("claude-fable-5") || m.starts_with("claude-mythos-5") => {
             ModelPricing {
@@ -41,8 +42,9 @@ fn lookup_pricing(model_name: &str) -> ModelPricing {
                 cache_write: per_m(12.5),
             }
         }
-        // Opus 4.5+ dropped to $5/$25 — only Opus 4.0/4.1 remain at $15/$75.
-        m if m.starts_with("claude-opus-4-5")
+        // Opus 5 and Opus 4.5+ are $5/$25 — only Opus 4.0/4.1 remain at $15/$75.
+        m if m.starts_with("claude-opus-5")
+            || m.starts_with("claude-opus-4-5")
             || m.starts_with("claude-opus-4-6")
             || m.starts_with("claude-opus-4-7")
             || m.starts_with("claude-opus-4-8") =>
@@ -269,6 +271,14 @@ mod tests {
         assert!((legacy - 90.0).abs() < 1e-6, "opus-4.1 should cost $15+$75, got {legacy}");
     }
 
+    #[test]
+    fn test_opus_5_pricing() {
+        // Opus 5 replaced Opus 4.8 as the worker default (2026-07-29) but is
+        // priced the same: $5+$25, not the legacy $15+$75 claude-opus-4 arm.
+        let cost = estimate_cost("anthropic/claude-opus-5", 1_000_000, 1_000_000, 0);
+        assert!((cost - 30.0).abs() < 1e-6, "opus-5 should cost $5+$25, got {cost}");
+    }
+
     #[test]
     fn test_fable_5_pricing() {
         let cost = estimate_cost("anthropic/claude-fable-5", 1_000_000, 1_000_000, 0);