diff --git a/mateclaw-server/src/main/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilder.java b/mateclaw-server/src/main/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilder.java
index fc436b84..3abe7ca0 100644
--- a/mateclaw-server/src/main/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilder.java
+++ b/mateclaw-server/src/main/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilder.java
@@ -137,11 +137,27 @@ public class AnthropicChatModelBuilder implements ChatModelBuilder {
     }
 
     /**
-     * True for any Claude 4.7+ model — the family that drops temperature /
-     * top_p / top_k and exposes the "xhigh" thinking tier between high and max.
+     * Detect the Claude Fable model line (e.g. {@code claude-fable-5}).
+     * Fable is a reasoning-first family that follows the same strict API
+     * contract as Claude 4.7+: temperature / top_p / top_k must be unset
+     * (any non-default value returns HTTP 400) and the "xhigh" adaptive
+     * thinking tier is available. Matching on the {@code claude-fable} token
+     * covers the direct-API id, the OpenRouter-prefixed form
+     * ({@code anthropic/claude-fable-5}), and future {@code claude-fable-N}
+     * revisions without a per-version code change.
+     */
+    static boolean isClaudeFable(String modelName) {
+        if (modelName == null) return false;
+        return modelName.toLowerCase().contains("claude-fable");
+    }
+
+    /**
+     * True for any modern Claude model that drops temperature / top_p / top_k
+     * and exposes the "xhigh" thinking tier between high and max — the Claude
+     * 4.7 / 4.8 generations and the Fable reasoning line.
      */
     static boolean isClaude47OrLater(String modelName) {
-        return isClaude47(modelName) || isClaude48(modelName);
+        return isClaude47(modelName) || isClaude48(modelName) || isClaudeFable(modelName);
     }
 
     AnthropicChatOptions buildAnthropicOptions(ModelConfigEntity runtimeModel) {
diff --git a/mateclaw-server/src/main/java/vip/mate/llm/service/ModelCapabilityService.java b/mateclaw-server/src/main/java/vip/mate/llm/service/ModelCapabilityService.java
index 23f87841..3eaba40e 100644
--- a/mateclaw-server/src/main/java/vip/mate/llm/service/ModelCapabilityService.java
+++ b/mateclaw-server/src/main/java/vip/mate/llm/service/ModelCapabilityService.java
@@ -86,6 +86,7 @@ public class ModelCapabilityService {
 
         // ===== Anthropic Claude =====
         // Vision yes (image), native video no — Anthropic's API only accepts images.
+        m.put("claude-fable",  EnumSet.of(Modality.VISION));
         m.put("claude-4.7",    EnumSet.of(Modality.VISION));
         m.put("claude-4.5",    EnumSet.of(Modality.VISION));
         m.put("claude-4",      EnumSet.of(Modality.VISION));
diff --git a/mateclaw-server/src/main/resources/db/migration/h2/V145__claude_fable_5_models.sql b/mateclaw-server/src/main/resources/db/migration/h2/V145__claude_fable_5_models.sql
new file mode 100644
index 00000000..7058a230
--- /dev/null
+++ b/mateclaw-server/src/main/resources/db/migration/h2/V145__claude_fable_5_models.sql
@@ -0,0 +1,25 @@
+-- Add Claude Fable 5 model entries to mate_model_config. Unlike earlier Claude
+-- families, the Fable rows live ONLY here, not in the data-{en,zh}.sql seed:
+-- Flyway runs every version (V1..) on a fresh database, so the migration seeds
+-- new installs and upgrades existing deployments alike. The trade-off is that
+-- the description below is English-only (seed files carry localized copy).
+--
+-- Fable 5 is a reasoning-first model with a 1M-token context window and native
+-- vision input. It follows the same strict API contract as Claude 4.7+:
+-- temperature / top_p / top_k must be NULL (otherwise HTTP 400), and the
+-- "xhigh" adaptive thinking tier is available. Both are handled in
+-- AnthropicChatModelBuilder via the isClaudeFable() / isClaude47OrLater()
+-- detectors. Vision capability is resolved in ModelCapabilityService.
+--
+-- MERGE INTO is the H2 idempotent upsert; running this twice is a no-op.
+-- Same V number is used in mysql/ for cross-dialect parity.
+
+MERGE INTO mate_model_config (id, name, provider, model_name, description, temperature, max_tokens, top_p, builtin, enabled, is_default, create_time, update_time, deleted)
+KEY (id)
+VALUES
+-- Direct Anthropic
+(1000000300, 'Claude Fable 5', 'anthropic', 'claude-fable-5', 'Anthropic Claude Fable 5 (1M context, vision, xhigh adaptive thinking)', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0),
+-- OpenRouter passthrough
+(1000000301, 'Claude Fable 5', 'openrouter', 'anthropic/claude-fable-5', 'Claude Fable 5 via OpenRouter', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0),
+-- Claude Code OAuth (Pro/Max subscription)
+(1000000302, 'Claude Fable 5', 'anthropic-claude-code', 'claude-fable-5', 'Claude Fable 5 via Claude Code Pro/Max subscription', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0);
diff --git a/mateclaw-server/src/main/resources/db/migration/mysql/V145__claude_fable_5_models.sql b/mateclaw-server/src/main/resources/db/migration/mysql/V145__claude_fable_5_models.sql
new file mode 100644
index 00000000..15fef7c3
--- /dev/null
+++ b/mateclaw-server/src/main/resources/db/migration/mysql/V145__claude_fable_5_models.sql
@@ -0,0 +1,37 @@
+-- Add Claude Fable 5 model entries to mate_model_config. Unlike earlier Claude
+-- families, the Fable rows live ONLY here, not in the data-mysql-{en,zh}.sql
+-- seed: Flyway runs every version (V1..) on a fresh database, so the migration
+-- seeds new installs and upgrades existing deployments alike. The trade-off is
+-- that the description below is English-only (seed files carry localized copy).
+--
+-- Fable 5 is a reasoning-first model with a 1M-token context window and native
+-- vision input. It follows the same strict API contract as Claude 4.7+:
+-- temperature / top_p / top_k must be NULL (otherwise HTTP 400), and the
+-- "xhigh" adaptive thinking tier is available. Both are handled in
+-- AnthropicChatModelBuilder via the isClaudeFable() / isClaude47OrLater()
+-- detectors. Vision capability is resolved in ModelCapabilityService.
+--
+-- INSERT ... ON DUPLICATE KEY UPDATE is the MySQL idempotent upsert.
+-- Same V number is used in h2/ for cross-dialect parity.
+
+INSERT INTO mate_model_config (id, name, provider, model_name, description, temperature, max_tokens, top_p, builtin, enabled, is_default, create_time, update_time, deleted)
+VALUES
+-- Direct Anthropic
+(1000000300, 'Claude Fable 5', 'anthropic', 'claude-fable-5', 'Anthropic Claude Fable 5 (1M context, vision, xhigh adaptive thinking)', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0),
+-- OpenRouter passthrough
+(1000000301, 'Claude Fable 5', 'openrouter', 'anthropic/claude-fable-5', 'Claude Fable 5 via OpenRouter', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0),
+-- Claude Code OAuth (Pro/Max subscription)
+(1000000302, 'Claude Fable 5', 'anthropic-claude-code', 'claude-fable-5', 'Claude Fable 5 via Claude Code Pro/Max subscription', NULL, 4096, NULL, TRUE, TRUE, FALSE, NOW(), NOW(), 0)
+ON DUPLICATE KEY UPDATE
+    name = VALUES(name),
+    provider = VALUES(provider),
+    model_name = VALUES(model_name),
+    description = VALUES(description),
+    temperature = VALUES(temperature),
+    max_tokens = VALUES(max_tokens),
+    top_p = VALUES(top_p),
+    builtin = VALUES(builtin),
+    enabled = VALUES(enabled),
+    is_default = VALUES(is_default),
+    update_time = VALUES(update_time),
+    deleted = VALUES(deleted);
diff --git a/mateclaw-server/src/test/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilderFableTest.java b/mateclaw-server/src/test/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilderFableTest.java
new file mode 100644
index 00000000..e1861dd8
--- /dev/null
+++ b/mateclaw-server/src/test/java/vip/mate/llm/chatmodel/AnthropicChatModelBuilderFableTest.java
@@ -0,0 +1,60 @@
+package vip.mate.llm.chatmodel;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * {@link AnthropicChatModelBuilder#isClaudeFable} must classify the Claude
+ * Fable reasoning line as a modern model so it inherits the strict 4.7+ API
+ * contract: temperature / top_p / top_k must be unset (any non-default value
+ * returns HTTP 400) and the "xhigh" adaptive thinking tier is available.
+ *
+ * <p>{@link AnthropicChatModelBuilder#isClaude47OrLater} unifies the gating
+ * logic across the 4.7 / 4.8 generations and the Fable family.</p>
+ */
+class AnthropicChatModelBuilderFableTest {
+
+    @Test
+    @DisplayName("isClaudeFable detects the direct-API and OpenRouter ids")
+    void detect_directAndOpenRouter() {
+        assertTrue(AnthropicChatModelBuilder.isClaudeFable("claude-fable-5"));
+        assertTrue(AnthropicChatModelBuilder.isClaudeFable("anthropic/claude-fable-5"));
+        // Case-insensitive
+        assertTrue(AnthropicChatModelBuilder.isClaudeFable("Claude-Fable-5"));
+    }
+
+    @Test
+    @DisplayName("isClaudeFable tolerates date-stamped and future revisions")
+    void detect_futureRevisions() {
+        assertTrue(AnthropicChatModelBuilder.isClaudeFable("claude-fable-5-20260609"));
+        assertTrue(AnthropicChatModelBuilder.isClaudeFable("claude-fable-6"));
+    }
+
+    @Test
+    @DisplayName("isClaudeFable ignores other Claude families and unrelated names")
+    void detect_negatives() {
+        assertFalse(AnthropicChatModelBuilder.isClaudeFable("claude-opus-4-8"));
+        assertFalse(AnthropicChatModelBuilder.isClaudeFable("claude-sonnet-4-6"));
+        // The "claude-fable" token guard prevents a stray "fable" elsewhere from matching.
+        assertFalse(AnthropicChatModelBuilder.isClaudeFable("some-fable-model"));
+    }
+
+    @Test
+    @DisplayName("isClaudeFable null-safe")
+    void detect_nullSafe() {
+        assertFalse(AnthropicChatModelBuilder.isClaudeFable(null));
+        assertFalse(AnthropicChatModelBuilder.isClaudeFable(""));
+    }
+
+    @Test
+    @DisplayName("isClaude47OrLater routes Fable onto the sampling-forbidden contract")
+    void claude47OrLater_includesFable() {
+        assertTrue(AnthropicChatModelBuilder.isClaude47OrLater("claude-fable-5"));
+        assertTrue(AnthropicChatModelBuilder.isClaude47OrLater("anthropic/claude-fable-5"));
+        // Sanity: existing generations still classify modern, legacy still falls through.
+        assertTrue(AnthropicChatModelBuilder.isClaude47OrLater("claude-opus-4-8"));
+        assertFalse(AnthropicChatModelBuilder.isClaude47OrLater("claude-opus-4-6"));
+    }
+}