Migrate piSessionService to ModelRuntime (slice 4)

Pass modelRuntime to createAgentSessionServices instead of authStorage +
modelRegistry; carry ModelRuntime on PiAgentSession; make modelRuntime a
required PiSessionService dependency (sessiond already injects auth.runtime).
Switch anthropicSubscriptionWarning to readStoredCredential, and rederive
model reads (availableModels/setModel/syncCurrentModelAuthWarning) via the
runtime (getAvailableSnapshot/getModel/hasConfiguredAuth). sessiond.ts and
piSessionService.ts now typecheck; only slice-5 test/support files remain.

src/server/sessions/piSessionService.ts

@@ -1,20 +1,21 @@
 import { statSync } from "node:fs";
+import { join } from "node:path";
 import { open, readFile, writeFile } from "node:fs/promises";
 import type { ImageContent } from "@earendil-works/pi-ai";
 import type { StreamFn } from "@earendil-works/pi-agent-core";
 import {
-  AuthStorage,
   createAgentSessionFromServices,
   createAgentSessionRuntime,
   createAgentSessionServices,
   createEditToolDefinition,
   defineTool,
-  ModelRegistry,
+  readStoredCredential,
   SessionManager,
   type AgentSessionRuntimeDiagnostic,
   type AgentSessionServices,
   type CreateAgentSessionRuntimeFactory,
   type EditToolDetails,
+  type ModelRuntime,
   type ResourceDiagnostic,
 } from "@earendil-works/pi-coding-agent";
 import type { ClientArchiveSessionsResponse, ClientCommand, ClientCommandResult, ClientMessagePage, ClientSession, ClientSessionCleanupExecuteResponse, ClientSessionCleanupPreviewResponse, ClientSessionModel, ClientSessionStatus, ClientThinkingLevel, SessionStreamSnapshot, SessionUiEvent } from "../types.js";
@@ -26,7 +27,6 @@ import { SessionCommandService } from "./sessionCommandService.js";
 import { SessionArchiveStore, type ArchivedSessionRecord, type ArchiveSessionInput } from "./sessionArchiveStore.js";
 import { findArchiveCandidateByIdOrPrefix, planSessionArchiveTree, type SessionArchiveTreeCandidate } from "./sessionArchiveTree.js";
 import type { ActiveSession } from "./sessionRuntimeStore.js";
-import { createModelRegistryForAgentDir, type AuthChange } from "./authService.js";
 import { deterministicSessionName, fallbackSessionName, generateShortSessionName } from "./sessionNameGenerator.js";
 import { computeEditPreview, type EditPreviewResult } from "./editPreview.js";
 import { attachmentsToInlineImages, saveAttachmentsToWorkspace } from "./attachmentService.js";
@@ -34,6 +34,7 @@ import { parsePromptAttachments } from "../../shared/promptAttachments.js";
 import type { SavedPromptAttachment, SessionBulkArchiveResponse, SessionBulkDeleteArchivedResponse, SessionBulkFailure, SessionBulkMutationRef, SessionWarning } from "../../shared/apiTypes.js";
 import type { SessionRouteLookup, SessionRouteRef, SessionRouteService } from "./sessionService.js";
 
+import { type AuthChange } from "./authService.js";
 import { canonicalizeStoredCwd, cwdPathsEqual } from "../workingDirectory.js";
 import type { WorkspaceActivityService } from "../activity/workspaceActivityService.js";
 import { createSpawnSessionToolDefinition, type SpawnSessionInvocation, type SpawnSessionResult } from "./spawnSessionTool.js";
@@ -171,7 +172,6 @@ interface BulkDeletePlanItem {
 }
 
 type AgentModel = NonNullable<SpawnSessionInvocation["model"]>;
-type ModelRegistryInstance = ReturnType<typeof ModelRegistry.create>;
 
 export interface PiSessionManager {
   getCwd(): string;
@@ -208,7 +208,7 @@ interface PiExtensionBindings {
 }
 
 export interface PiAgentSession {
-  modelRegistry: ModelRegistryInstance;
+  modelRuntime: ModelRuntime;
   /**
    * Narrow read/write of the SDK `SettingsManager`, exposing only the warning
    * suppression flags consumed here (e.g. `anthropicExtraUsage`). Used to gate
@@ -383,11 +383,12 @@ const ANTHROPIC_EXTRA_USAGE_DISMISS_ID = "anthropicExtraUsage";
  * synchronous live status computation.
  */
 export function anthropicSubscriptionWarning(
-  session: Pick<PiAgentSession, "model" | "modelRegistry" | "settingsManager">,
+  session: Pick<PiAgentSession, "model" | "settingsManager">,
+  authPath?: string,
 ): SessionWarning | undefined {
   if (session.settingsManager.getWarnings().anthropicExtraUsage === false) return undefined;
   if (session.model?.provider !== "anthropic") return undefined;
-  const credential = session.modelRegistry.authStorage.get("anthropic");
+  const credential = readStoredCredential("anthropic", authPath);
   if (credential === undefined) return undefined;
   const isSubscriptionAuth = credential.type === "oauth"
     ? true
@@ -487,14 +488,13 @@ export function createPiWebCustomToolDefinitions(
 }
 
 function createDefaultRuntimeFactory(
-  authStorage: AuthStorage,
+  modelRuntime: ModelRuntime,
-  modelRegistry: ModelRegistryInstance,
   sessionManagers: Pick<PiSessionManagerGateway, "open">,
   spawn?: SpawnSessionFn,
   subsessions?: SubsessionToolDeps,
 ): PiWebCreateAgentSessionRuntimeFactory {
   return async ({ cwd, agentDir, sessionManager, sessionStartEvent, initialModel, delegationToolsEnabled }) => {
-    const services = await createAgentSessionServices({ cwd, agentDir, authStorage, modelRegistry });
+    const services = await createAgentSessionServices({ cwd, agentDir, modelRuntime });
     const resolvedDelegationToolsEnabled = delegationToolsEnabled
       ?? await sessionAllowsDelegationTools(sessionManager, sessionManagers);
     const customTools = createPiWebCustomToolDefinitions(cwd, resolvedDelegationToolsEnabled, spawn, subsessions);
@@ -539,7 +539,7 @@ export interface PiSessionServiceDependencies {
   archiveStore?: SessionArchiveRepository;
   createRuntime?: PiWebCreateAgentSessionRuntimeFactory;
   createAgentRuntime?: CreateAgentRuntime;
-  modelRegistry?: ModelRegistryInstance;
+  modelRuntime: ModelRuntime;
   heartbeatIntervalMs?: number;
   workspaceActivity?: Pick<WorkspaceActivityService, "applySessionStatus" | "applySessionActivity" | "removeSession" | "reconcileSessionActivity">;
   /**
@@ -589,7 +589,7 @@ export class PiSessionService implements SessionRouteService {
   private readonly sessionManager: PiSessionManagerGateway;
   private readonly createRuntime: PiWebCreateAgentSessionRuntimeFactory;
   private readonly createAgentRuntime: CreateAgentRuntime;
-  private readonly modelRegistry: ModelRegistryInstance;
+  private readonly modelRuntime: ModelRuntime;
   private readonly workspaceActivity: Pick<WorkspaceActivityService, "applySessionStatus" | "applySessionActivity" | "removeSession" | "reconcileSessionActivity"> | undefined;
   private readonly spawnTargets: SpawnTargetResolver | undefined;
   private readonly logger: PiSessionLogger;
@@ -599,7 +599,7 @@ export class PiSessionService implements SessionRouteService {
     this.archiveStore = deps.archiveStore ?? new SessionArchiveStore();
     this.agentDir = deps.agentDir;
     this.sessionManager = deps.sessionManager;
-    this.modelRegistry = deps.modelRegistry ?? createModelRegistryForAgentDir(this.agentDir);
+    this.modelRuntime = deps.modelRuntime;
     this.spawnTargets = deps.spawnTargets;
     this.logger = deps.logger ?? noopLogger;
     this.now = deps.now ?? (() => new Date());
@@ -607,8 +607,7 @@ export class PiSessionService implements SessionRouteService {
     // also require the spawn capability (they share its project-scope resolver).
     const subsessionsActive = this.spawnTargets !== undefined && deps.subsessionsEnabled === true;
     this.createRuntime = deps.createRuntime ?? createDefaultRuntimeFactory(
-      this.modelRegistry.authStorage,
+      this.modelRuntime,
-      this.modelRegistry,
       this.sessionManager,
       this.spawnTargets === undefined ? undefined : (input) => this.spawnSession(input),
       !subsessionsActive ? undefined : {
@@ -1159,22 +1158,22 @@ export class PiSessionService implements SessionRouteService {
 
   async availableModels(ref: PiSessionLookup): Promise<ClientSessionModel[]> {
     const session = await this.getOrOpen(ref);
-    session.modelRegistry.refresh();
+    await session.modelRuntime.refresh();
     const models = session.scopedModels.length > 0
       ? session.scopedModels.map((scoped) => scoped.model)
-      : session.modelRegistry.getAvailable();
+      : session.modelRuntime.getAvailableSnapshot();
     return models.map(modelToClientModel);
   }
 
   async setModel(ref: PiSessionLookup, provider: string, modelId: string): Promise<ClientSessionStatus> {
     await this.assertWritable(ref);
     const session = await this.getOrOpen(ref);
-    session.modelRegistry.refresh();
+    await session.modelRuntime.refresh();
     const candidates = session.scopedModels.length > 0
       ? session.scopedModels.map((scoped) => scoped.model)
-      : session.modelRegistry.getAvailable();
+      : session.modelRuntime.getAvailableSnapshot();
     const model = candidates.find((candidate) => candidate.provider === provider && candidate.id === modelId)
-      ?? session.modelRegistry.find(provider, modelId);
+      ?? session.modelRuntime.getModel(provider, modelId);
     if (model === undefined) throw new Error(`Model not found: ${provider}/${modelId}`);
     await session.setModel(model);
     this.publishActivity(session, `model: ${model.id}`, "idle", model.provider);
@@ -2020,10 +2019,11 @@ export class PiSessionService implements SessionRouteService {
   }
 
   applyAuthChange(change: AuthChange = {}): void {
-    this.modelRegistry.refresh();
+    // The shared model runtime is refreshed by AuthService before it emits the
+    // change (and every session shares that runtime), so no refresh is needed
+    // here — this keeps the subscribe callback synchronous.
     for (const active of this.active.values()) {
       const { session } = active.runtime;
-      session.modelRegistry.refresh();
       this.syncCurrentModelAuthWarning(session, change.removedProviderId);
       this.publishStatus(session);
     }
@@ -2034,9 +2034,9 @@ export class PiSessionService implements SessionRouteService {
     if (model === undefined) return;
     if (model.provider === "unknown" && model.id === "unknown") return;
     const warningKey = authLossWarningKey(session.sessionId, model.provider, model.id);
-    const registered = session.modelRegistry.find(model.provider, model.id);
+    const registered = session.modelRuntime.getModel(model.provider, model.id);
     if (registered === undefined) return;
-    if (session.modelRegistry.hasConfiguredAuth(registered)) {
+    if (session.modelRuntime.hasConfiguredAuth(model.provider)) {
       this.authLossWarnings.delete(warningKey);
       return;
     }
@@ -2182,7 +2182,7 @@ export class PiSessionService implements SessionRouteService {
   private warningsForSession(session: PiAgentSession): SessionWarning[] {
     const runtime = this.active.get(session.sessionId)?.runtime;
     const warnings = runtime === undefined ? [] : collectRuntimeWarnings(runtime);
-    const anthropic = anthropicSubscriptionWarning(session);
+    const anthropic = anthropicSubscriptionWarning(session, join(this.agentDir, "auth.json"));
     if (anthropic !== undefined) warnings.push(anthropic);
     return warnings;
   }