diff --git a/apps/console/src/components/chat/ChatPage.tsx b/apps/console/src/components/chat/ChatPage.tsx
index 70ce6050..50c1dc9f 100644
--- a/apps/console/src/components/chat/ChatPage.tsx
+++ b/apps/console/src/components/chat/ChatPage.tsx
@@ -49,7 +49,7 @@ const MESSAGE_PERSIST_DEBOUNCE_MS = 500;
 const EMPTY_CAPABILITIES: readonly CapabilityItem[] = [];
 
 /** A failed chat request, kept with the evidence needed to describe it. */
-type ChatFailure = { code: string; door?: string; status?: number };
+type ChatFailure = { code: string; door?: string; status?: number; reason?: string };
 
 /**
  * Classify a rejected chat request.
@@ -62,14 +62,23 @@ type ChatFailure = { code: string; door?: string; status?: number };
  */
 function chatFailure(error: unknown, door: string): ChatFailure {
   if (error instanceof ChatWireError) {
+    const code = error.wireCode ?? 'console_chat_wire_failed';
     return {
-      code: error.wireCode ?? 'console_chat_wire_failed',
+      code,
       door: error.door,
       status: error.status ?? undefined,
+      // These routes wrap an inner failure and put its reason in `message`.
+      // That reason is the only part naming what actually broke, so keep it
+      // unless it just repeats the code the sentence already covers.
+      reason: error.message && error.message !== code ? error.message : undefined,
     };
   }
   // fetch itself rejected, so there is no status: the request never landed.
-  return { code: 'console_chat_wire_failed', door };
+  return {
+    code: 'console_chat_wire_failed',
+    door,
+    reason: error instanceof Error ? error.message : undefined,
+  };
 }
 
 function connectionFor(status: number | null, error?: string | null): ConnectionState {
@@ -459,6 +468,7 @@ export function ChatPage({
     ? degradationFor(loadError.code, {
         door: loadError.door,
         status: loadError.status,
+        reason: loadError.reason,
       })
     : connection === 'disconnected'
       ? degradationFor('console_data_api_unreachable', transportOrigin)
diff --git a/apps/console/src/lib/degradation.test.ts b/apps/console/src/lib/degradation.test.ts
index cc8bb76c..726064e0 100644
--- a/apps/console/src/lib/degradation.test.ts
+++ b/apps/console/src/lib/degradation.test.ts
@@ -140,6 +140,59 @@ describe('degradationFor origin evidence', () => {
     expect(chat.detail).toContain('502');
   });
 
+  // The failing route knows why it failed and says so in its body. Dropping
+  // that left the reader with a category ("answered 502") and no cause, which
+  // is what turned a real 502 into another round trip.
+  it('surfaces the upstream reason alongside the door and status', () => {
+    const result = degradationFor('project_catalog_failed', {
+      door: '/api/chat/projects',
+      status: 502,
+      reason: 'objects/query failed: 502',
+    });
+    expect(result.cause).toBe('The chat project list could not be read.');
+    expect(result.detail).toContain('/api/chat/projects');
+    expect(result.detail).toContain('502');
+    expect(result.detail).toContain('objects/query failed');
+  });
+
+  // CS15 still holds: a bare wire code is not prose, so it renders as its
+  // sentence rather than as the identifier.
+  it('translates a wire-code reason into its sentence', () => {
+    const result = degradationFor('project_catalog_failed', {
+      door: '/api/chat/projects',
+      status: 502,
+      reason: 'console_data_api_unreachable',
+    });
+    expect(result.detail).toContain('The data API is unreachable.');
+    expect(result.detail).not.toContain('console_data_api_unreachable');
+  });
+
+  it('bounds a runaway reason so a stack trace cannot become the banner', () => {
+    const result = degradationFor('project_catalog_failed', {
+      door: '/api/chat/projects',
+      status: 502,
+      reason: 'x'.repeat(500),
+    });
+    expect(result.detail!.length).toBeLessThan(320);
+    expect(result.detail).toContain('...');
+  });
+
+  it('every chat route error code has a sentence of its own', () => {
+    const emitted = [
+      'project_catalog_failed', 'project_write_failed', 'project_select_failed',
+      'thread_catalog_failed', 'thread_read_failed', 'thread_create_failed',
+      'thread_update_failed', 'thread_not_found', 'attachment_upload_failed',
+      'file_required', 'invalid_body', 'tenant_connector_unavailable',
+      'web_search_requires_principal', 'console_chat_wire_failed',
+      'web_search_unavailable',
+    ];
+    const generic = degradationFor('a_code_that_is_not_mapped_at_all').cause;
+    for (const code of emitted) {
+      expect(degradationFor(code).cause, `${code} fell through to the generic sentence`)
+        .not.toBe(generic);
+    }
+  });
+
   it('still keeps the wire code out of what the user sees', () => {
     const result = degradationFor('console_data_api_unreachable', {
       door: '/api/objects/views',
diff --git a/apps/console/src/lib/degradation.ts b/apps/console/src/lib/degradation.ts
index 8a4dad19..7217ea45 100644
--- a/apps/console/src/lib/degradation.ts
+++ b/apps/console/src/lib/degradation.ts
@@ -29,6 +29,14 @@ export type DegradationOrigin = {
   host?: string;
   /** HTTP status, when the request was answered at all. Omit for no answer. */
   status?: number;
+  /**
+   * What the failing route said went wrong, when it said anything.
+   *
+   * A route that wraps an inner failure knows the reason and puts it in its
+   * body; dropping it leaves the reader with a category ("answered 502") and
+   * no cause. Rendered through `readableReason`, which keeps CS15 intact.
+   */
+  reason?: string;
 };
 
 type DegradationTemplate =
@@ -104,6 +112,86 @@ const WIRE_MAP: Record<string, DegradationTemplate> = {
     actionLabel: 'Retry',
     door: 'The chat wire',
   },
+  // Every code the /api/chat/* routes can emit. Before these, all of them fell
+  // through to GENERIC_UNAVAILABLE, so a failed project read, a failed thread
+  // write and a missing attachment all said "This surface cannot render right
+  // now." An unmapped code is not a neutral default: it is a sentence that
+  // cannot be acted on.
+  project_catalog_failed: {
+    level: 'unavailable',
+    cause: 'The chat project list could not be read.',
+    actionLabel: 'Retry',
+    door: 'The chat project catalog',
+  },
+  project_write_failed: {
+    level: 'unavailable',
+    cause: 'That chat project could not be saved.',
+    actionLabel: 'Retry',
+    door: 'The chat project catalog',
+  },
+  project_select_failed: {
+    level: 'unavailable',
+    cause: 'That project could not be made active.',
+    actionLabel: 'Retry',
+    door: 'The chat project catalog',
+  },
+  thread_catalog_failed: {
+    level: 'unavailable',
+    cause: 'The thread list could not be read.',
+    actionLabel: 'Retry',
+    door: 'The chat thread catalog',
+  },
+  thread_read_failed: {
+    level: 'unavailable',
+    cause: 'That thread could not be read.',
+    actionLabel: 'Retry',
+    door: 'The chat thread catalog',
+  },
+  thread_create_failed: {
+    level: 'unavailable',
+    cause: 'That thread could not be created.',
+    actionLabel: 'Retry',
+    door: 'The chat thread catalog',
+  },
+  thread_update_failed: {
+    level: 'unavailable',
+    cause: 'That thread could not be saved.',
+    actionLabel: 'Retry',
+    door: 'The chat thread catalog',
+  },
+  thread_not_found: {
+    level: 'unavailable',
+    cause: 'That thread no longer exists.',
+    door: 'The chat thread catalog',
+  },
+  attachment_upload_failed: {
+    level: 'unavailable',
+    cause: 'That attachment could not be uploaded.',
+    actionLabel: 'Retry',
+    door: 'The chat attachment upload',
+  },
+  file_required: {
+    level: 'unavailable',
+    cause: 'That upload arrived without a file.',
+    door: 'The chat attachment upload',
+  },
+  invalid_body: {
+    level: 'unavailable',
+    cause: 'The console sent a request this route could not read.',
+    door: 'The chat wire',
+  },
+  tenant_connector_unavailable: {
+    level: 'unavailable',
+    cause: 'No connector is available for this tenant.',
+    actionLabel: 'Open Account',
+    door: 'The chat wire',
+  },
+  web_search_requires_principal: {
+    level: 'unavailable',
+    cause: 'Web search needs a signed-in principal.',
+    actionLabel: 'Open Account',
+    door: 'Web search',
+  },
   web_search_unavailable: {
     level: 'reduced',
     cause: 'Web search is unavailable.',
@@ -202,18 +290,47 @@ export function degradationFor(
  * credential problem rather than an outage. Returns undefined when there is
  * nothing concrete to say, so no caller is forced to show an empty line.
  */
+/**
+ * Render an upstream reason without leaking a wire code to the reader.
+ *
+ * Inner failures often surface as a bare code (`console_data_api_unreachable`)
+ * rather than prose. CS15 keeps codes off the screen, so a code is translated
+ * to its sentence; anything else is real prose already and passes through,
+ * bounded so a stack trace cannot become the banner.
+ */
+function readableReason(reason: string | undefined): string | undefined {
+  const trimmed = reason?.trim();
+  if (!trimmed) return undefined;
+  const rendered = /^[a-z][a-z0-9_]*$/.test(trimmed)
+    // An unmapped bare code has no sentence to show, and inventing one would
+    // hide the only identifier the reader could search for.
+    ? (WIRE_MAP[trimmed]?.cause ?? trimmed)
+    : trimmed;
+  // Bound at the exit, not inside one branch. The code-shaped test matches any
+  // run of lowercase, so a long token took the other path and escaped the cap.
+  return rendered.length > 160 ? `${rendered.slice(0, 157)}...` : rendered;
+}
+
 export function describeOrigin(origin: DegradationOrigin | undefined): string | undefined {
   if (!origin) return undefined;
   const { door, host, status } = origin;
-  if (!door && !host && status === undefined) return undefined;
+  const reason = readableReason(origin.reason);
+  if (!door && !host && status === undefined) return reason;
 
   const subject = [door ?? 'The request', host ? `at ${host}` : null].filter(Boolean).join(' ');
+  // The reason is the innermost thing known about the failure, so it goes last
+  // and never replaces the door and status a reader needs to locate it.
+  const withReason = (sentence: string) => (reason ? `${sentence} ${reason}` : sentence);
 
   if (status === undefined) {
-    return `${subject} did not answer. That is DNS, the network, or a blocked origin, not a status code.`;
+    return withReason(
+      `${subject} did not answer. That is DNS, the network, or a blocked origin, not a status code.`,
+    );
   }
   if (status === 401) {
-    return `${subject} answered 401. The request was not authenticated, which is a credential problem rather than an outage.`;
+    return withReason(
+      `${subject} answered 401. The request was not authenticated, which is a credential problem rather than an outage.`,
+    );
   }
   if (status === 403) {
     // Not the same failure as 401, and saying so matters. connectionFor maps
@@ -221,12 +338,16 @@ export function describeOrigin(origin: DegradationOrigin | undefined): string |
     // active_workspace_claim_required and active_workspace_membership_refused.
     // In those cases the credential is fine and simply does not reach this
     // workspace, so "fix your credential" would send the reader the wrong way.
-    return `${subject} answered 403. The credential was accepted but refused for this workspace, which is not an outage.`;
+    return withReason(
+      `${subject} answered 403. The credential was accepted but refused for this workspace, which is not an outage.`,
+    );
   }
   if (status === 404) {
-    return `${subject} answered 404. Check the configured URL before assuming the service is down.`;
+    return withReason(
+      `${subject} answered 404. Check the configured URL before assuming the service is down.`,
+    );
   }
-  return `${subject} answered ${status}.`;
+  return withReason(`${subject} answered ${status}.`);
 }
 
 /** Collapse a list of missing capability codes into one reduced marker. */