fix(apiproxy): title-invalid only for the input's fault, presentable messages

The rename impl narrows on SessionTitleInvalidError: only an
empty-normalizing title maps to title-invalid (its message renders verbatim
in the rename dialog alert), while liveness/disposal races fall to internal;
the absent-service message trims to one presentable sentence. rpc-schemas
gains the title-invalid accept/missing-details lines; cosmetic ordering
(type-only import comment, tsconfig reference, schema import order) restored.

packages/host/apiproxy/src/api-proxy.ts

@@ -36,10 +36,10 @@ import type {} from '@deepseek-ai/dsh-session-projection-cache'
 import { GoalError } from '@deepseek-ai/dsh-goal'
 import type { GoalRef as CoreGoalRef } from '@deepseek-ai/dsh-goal'
 // Type-only edges: resolve `ctx.get('commands')`, the `commands/change` event, and `ctx.get('skills')`.
-// Type-only edge: resolves `ctx.get('sessionTitle')` for the rename impl.
-import type {} from '@deepseek-ai/dsh-session-title'
 import type {} from '@deepseek-ai/dsh-commands'
 import type {} from '@deepseek-ai/dsh-skill'
+// Value edge: the rename impl narrows the title service's validation failure; the import also resolves `ctx.get('sessionTitle')`.
+import { SessionTitleInvalidError } from '@deepseek-ai/dsh-session-title'
 import type { CallId } from '@deepseek-ai/dsh-llm/brand'
 import type { ApprovalOutcome, ApprovalRequestId } from '@deepseek-ai/dsh-user-approval'
 // Side-effect type import: resolves the `approval/request` waterfall and
@@ -1057,16 +1057,26 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
         if ('error' in found) return err(request, found.error)
         const titles = ctx.get('sessionTitle')
         if (titles === undefined) {
-          return err(request, { code: 'internal', message: 'session-title service is absent: this deployment does not mount @deepseek-ai/dsh-session-title in its composition (cordis.yml or explicit assembly)', details: {} })
+          return err(request, { code: 'internal', message: 'renaming is unavailable: this deployment mounts no session-title service', details: {} })
         }
         try {
           const accepted = titles.rename(found.agent.session, title)
           return ok(request, { title: accepted.title, seq: accepted.eventSeq })
         } catch (error: unknown) {
+          // Only the input's fault maps to title-invalid (the message is
+          // product-user-visible in the rename dialog); liveness and disposal
+          // races are deployment trouble, not a bad title.
+          if (error instanceof SessionTitleInvalidError) {
+            return err(request, {
+              code: 'title-invalid',
+              message: error.message,
+              details: { sessionId },
+            })
+          }
           return err(request, {
-            code: 'title-invalid',
-            message: `rename rejected for session "${sessionId}": ${String(error)}`,
-            details: { sessionId },
+            code: 'internal',
+            message: `failed to rename session "${sessionId}": ${String(error)}`,
+            details: {},
           })
         }
       },

packages/host/apiproxy/src/fetch/client.ts

@@ -20,11 +20,11 @@ import {
 import {
   sessionCancelValueSchema,
   sessionCreateValueSchema,
-  sessionRenameValueSchema,
   sessionHistoryValueSchema,
   sessionListValueSchema,
   sessionModelsValueSchema,
   sessionPromptValueSchema,
+  sessionRenameValueSchema,
   sessionSelectModelValueSchema,
 } from '../api/sessions.schema.ts'
 import {

packages/host/apiproxy/src/fetch/handler.ts

@@ -17,11 +17,11 @@ import { clientRequestSchema, clientResponseSchema } from '../api/rpc.schema.ts'
 import {
   sessionCancelRequestSchema,
   sessionCreateRequestSchema,
-  sessionRenameRequestSchema,
   sessionHistoryRequestSchema,
   sessionListRequestSchema,
   sessionModelsRequestSchema,
   sessionPromptRequestSchema,
+  sessionRenameRequestSchema,
   sessionSelectModelRequestSchema,
 } from '../api/sessions.schema.ts'
 import {