fix(coding): preserve runtime model and failure contracts

electron/coding-runtime/conversation-service.ts

@@ -339,11 +339,24 @@ export class CodingConversationService {
   }
 
   async setModel(conversationId: string, model: ProductModelRef): Promise<ConversationModelState> {
-    const { project } = await this.projects.findActiveConversation(conversationId);
+    const { project, conversation } = await this.projects.findActiveConversation(conversationId);
     let selected: ProductModelRef;
     try {
       selected = await this.runtime.validateModel(model);
     } catch (error) { runtimeError(error); }
+    if (conversation.modelResolution === 'resolved' && conversation.model) {
+      await this.ensurePrepared(conversationId);
+      let state: ConversationModelState;
+      try {
+        state = await this.runtime.setModel({
+          conversationId,
+          accountId: selected.accountId,
+          modelId: selected.modelId,
+        });
+      } catch (error) { runtimeError(error); }
+      await persist(() => this.projects.conversationStore(project.path).setModelState(conversationId, state));
+      return state;
+    }
     const state: ConversationModelState = {
       model: selected,
       modelResolution: 'resolved',
@@ -364,7 +377,7 @@ export class CodingConversationService {
     const { project } = await this.projects.findActiveConversation(conversationId);
     try {
       const state = await this.runtime.setThinking({ conversationId, thinkingLevel });
-      await this.projects.conversationStore(project.path).setModelState(conversationId, state);
+      await persist(() => this.projects.conversationStore(project.path).setModelState(conversationId, state));
       return state;
     } catch (error) { runtimeError(error); }
   }

electron/coding-runtime/in-memory-conversation-runtime.ts

@@ -2,8 +2,6 @@ import type {
   CodingConversationRuntime,
   CodingRuntimeCommand,
   CodingRuntimeDiagnostics,
-  CodingRuntimeErrorCode,
-  CodingRuntimePublicError,
   ConversationModelState,
   ConversationInteraction,
   ConversationInteractionResponse,
@@ -22,22 +20,14 @@ import type {
   SetConversationModelInput,
   SetThinkingLevelInput,
 } from './contracts';
+import { CodingRuntimeContractError } from './runtime-errors';
+export { CodingRuntimeContractError } from './runtime-errors';
 import {
   createConversationReducerState,
   reduceConversationPatch,
   type ConversationReducerState,
 } from './conversation-reducer';
 
-export class CodingRuntimeContractError extends Error {
-  readonly publicError: CodingRuntimePublicError;
-
-  constructor(code: CodingRuntimeErrorCode, message: string, recoverable: boolean) {
-    super(message);
-    this.name = 'CodingRuntimeContractError';
-    this.publicError = { code, message, recoverable };
-  }
-}
-
 export interface InMemoryConversationRuntimeOptions {
   snapshots?: ConversationSnapshot[];
   commands?: CodingRuntimeCommand[];

electron/coding-runtime/pi/runtime.ts

@@ -38,7 +38,7 @@ import {
   reduceConversationPatch,
   type ConversationReducerState,
 } from '../conversation-reducer';
-import { CodingRuntimeContractError } from '../in-memory-conversation-runtime';
+import { CodingRuntimeContractError } from '../runtime-errors';
 import {
   PiEventProjector,
   type PiEventProjectorOptions,

electron/coding-runtime/pi/session-registry.ts

@@ -12,6 +12,7 @@ import type {
   ConversationModelState,
   PrepareConversationInput,
 } from '../contracts';
+import { CodingRuntimeContractError } from '../runtime-errors';
 
 export interface PiRegisteredConversation {
   projectPath: string;
@@ -22,6 +23,7 @@ export interface PiRegisteredConversation {
 
 export interface PiSessionRegistryOptions {
   projectStore: CodingProjectStore;
+  createConversationStore?: typeof createCodingConversationStore;
 }
 
 interface RegistryRecord extends PiRegisteredConversation {
@@ -55,11 +57,13 @@ function sameModelState(left: ConversationModelState, right: ConversationModelSt
 
 export class PiSessionRegistry {
   private readonly projectStore: CodingProjectStore;
+  private readonly createConversationStore: typeof createCodingConversationStore;
   private readonly records = new Map<string, RegistryRecord>();
   private readonly prepareFlights = new Map<string, Promise<RegistryRecord>>();
 
   constructor(options: PiSessionRegistryOptions) {
     this.projectStore = options.projectStore;
+    this.createConversationStore = options.createConversationStore ?? createCodingConversationStore;
   }
 
   async prepare(input: PrepareConversationInput): Promise<PiRegisteredConversation> {
@@ -71,7 +75,9 @@ export class PiSessionRegistry {
     createBinding: () => Promise<PiSessionBinding>,
   ): Promise<PiRegisteredConversation> {
     const record = await this.prepareRecord(input);
-    const conversation = await record.store.ensureSessionBinding(input.conversationId, createBinding);
+    const conversation = await this.persistWrite(
+      () => record.store.ensureSessionBinding(input.conversationId, createBinding),
+    );
     record.conversation = conversation;
     record.session = {
       piSessionId: conversation.piSessionId as string,
@@ -86,7 +92,9 @@ export class PiSessionRegistry {
   ): Promise<ConversationModelState> {
     const record = this.records.get(conversationId);
     if (!record) throw new Error('Conversation is not registered');
-    record.conversation = await record.store.setModelState(conversationId, model);
+    record.conversation = await this.persistWrite(
+      () => record.store.setModelState(conversationId, model),
+    );
     return modelStateOf(record.conversation);
   }
 
@@ -118,7 +126,7 @@ export class PiSessionRegistry {
       candidate.id === input.agentId && candidate.enabled && !candidate.archivedAt
     ));
     if (!agent) throw new Error('Coding Agent does not exist');
-    const store = createCodingConversationStore(project.path);
+    const store = this.createConversationStore(project.path);
     const conversation = await store.get(input.conversationId);
     if (!conversation || conversation.agentId !== input.agentId) {
       throw new Error('Coding Conversation does not exist for the selected Agent');
@@ -138,4 +146,17 @@ export class PiSessionRegistry {
     this.records.set(input.conversationId, record);
     return record;
   }
+
+  private async persistWrite<T>(operation: () => Promise<T>): Promise<T> {
+    try {
+      return await operation();
+    } catch (error) {
+      if (error instanceof CodingRuntimeContractError) throw error;
+      throw new CodingRuntimeContractError(
+        'CODING_STORAGE_WRITE_FAILED',
+        'Coding Conversation state could not be persisted',
+        true,
+      );
+    }
+  }
 }

electron/coding-runtime/runtime-errors.ts

@@ -0,0 +1,14 @@
+import type {
+  CodingRuntimeErrorCode,
+  CodingRuntimePublicError,
+} from './contracts';
+
+export class CodingRuntimeContractError extends Error {
+  readonly publicError: CodingRuntimePublicError;
+
+  constructor(code: CodingRuntimeErrorCode, message: string, recoverable: boolean) {
+    super(message);
+    this.name = 'CodingRuntimeContractError';
+    this.publicError = { code, message, recoverable };
+  }
+}