feat(feedback): disclose session sharing in the /feedback acknowledgement

The /feedback acknowledgement now echoes the receiving session id and
reports the mounted telemetry backend's sharing policy: the telemetry seam
exposes a backend-independent TelemetrySharingStatus through a required
abstract sharing member on the Telemetry service, the OTel backend maps its
mode onto it, and the command appends one policy-only sharing sentence
(full / feedback-only / disabled / not configured) to the acknowledgement.
The web client renders the text through the existing command row without a
client change; a new assembled-browser e2e mounts the shipped telemetry row
in FULL mode against a local dead endpoint and pins the shipped default
sentence as a keyless golden.

packages/session/session-telemetry-otel/src/index.ts

@@ -22,6 +22,7 @@ import {
   type TelemetryBackend,
   type TelemetryRecord,
   type TelemetrySeverity,
+  type TelemetrySharingStatus,
 } from '@deepseek-ai/dsh-session-telemetry'
 import { APP_IDENTITY } from '@deepseek-ai/dsh-llm'
 import { getOrCreateAnonymousUserId } from '@deepseek-ai/dsh-user-id'
@@ -71,6 +72,17 @@ function assertNever(value: never): never {
   throw new Error(`session-telemetry-otel: unsupported mode ${JSON.stringify(value)}`)
 }
 
+/** Map the serialized mode onto the seam's backend-independent sharing vocabulary. */
+function sharingStatusFor(mode: TelemetryMode): TelemetrySharingStatus {
+  switch (mode) {
+    case TelemetryMode.FULL: return 'full'
+    case TelemetryMode.FEEDBACK_ONLY: return 'feedback-only'
+    case TelemetryMode.DISABLED: return 'disabled'
+    /* v8 ignore next 2 -- resolveMode already rejected unknown values before this switch; the closed enum cannot reach the default. */
+    default: return assertNever(mode)
+  }
+}
+
 /**
  * Plugin configuration: one sharing policy, two verbatim SDK option objects,
  * and one DSH-owned shutdown bound. Uploading modes validate their endpoint
@@ -139,10 +151,12 @@ export class TelemetryOtel extends Telemetry {
   private readonly directEmit: TelemetryBackend['emit']
   private readonly provider: LoggerProvider | undefined
   private readonly shutdownTimeoutMillis: number
+  override readonly sharing: TelemetrySharingStatus
 
   constructor(ctx: Context, config: Config) {
     const mode = resolveMode(config.mode)
     super(ctx)
+    this.sharing = sharingStatusFor(mode)
     if (mode === TelemetryMode.DISABLED) {
       this.directEmit = DROP_RECORD
       this.provider = undefined