Merge pull request #514 from irisitymichaelgrundberg/feat/claude-session-model

feat(sessions): accept a per-session Claude model on POST /api/sessions

src/session.ts

@@ -1827,6 +1827,7 @@ export class Session extends EventEmitter {
       ompConfig: this._ompConfig,
       resumeSessionId: this._resumeSessionId,
       effort: this._effort,
+      model: this._model,
       customModel: this.customModel,
       // COD-118: runtime-only — surfaced so the frontend can require explicit user
       // intent before restarting a crash-looped session. Deliberately NOT restored

src/types/session.ts

@@ -807,6 +807,13 @@ export interface SessionState {
   resumeSessionId?: string;
   /** Claude CLI effort level (soft default via --settings, switchable in-session via /effort) */
   effort?: EffortLevel;
+  /**
+   * The model the session was LAUNCHED with (`--model`): the caller's per-session `model`, or
+   * the app-wide default when there was none. Persisted so a recovered session relaunches on
+   * the same model rather than whatever the default is by then. Not `cliModel`, which is what
+   * the CLI's banner reports.
+   */
+  model?: string;
   /**
    * Custom Model Endpoint Profiles (docs/custom-model-endpoints-plan.md): the custom
    * OpenAI-compatible endpoint (local or cloud) this session's CLI is currently pointed

src/web/routes/reboot-restore-routes.ts

@@ -195,6 +195,7 @@ export function registerRebootRestoreRoutes(app: FastifyInstance, ctx: RebootRes
               (saved as { __envOverrides?: Record<string, string> }).__envOverrides
             ),
             effort: saved.effort,
+            model: saved.model,
             attachmentHistory:
               (saved as { __attachmentHistory?: SessionAttachmentHistoryItem[] }).__attachmentHistory ??
               saved.attachmentHistory,

src/web/routes/session-routes.ts

@@ -889,6 +889,15 @@ export function registerSessionRoutes(
     if (capMsg) return createErrorResponse(ApiErrorCode.OPERATION_FAILED, capMsg);
 
     const body = parseBody(CreateSessionSchema, req.body);
+    // The top-level `model` is Claude's per-session `--model`. Every other CLI takes its model
+    // in its own config object (`codexConfig.model` and so on), so a `model` here would be
+    // dropped without a word; refuse it before anything is written for the session.
+    if (body.model && getCli(body.mode ?? 'claude')?.capabilities.model.source !== 'claude-settings-file') {
+      return createErrorResponse(
+        ApiErrorCode.INVALID_INPUT,
+        'model applies to claude sessions only; other CLIs take their model in their own config object, such as codexConfig.model'
+      );
+    }
     let workingDir = body.workingDir || process.cwd();
     let remote = undefined;
 
@@ -1074,9 +1083,10 @@ export function registerSessionRoutes(
     // genuinely different mechanisms:
     //   'flag'                 — the CLI takes --model, so read the value the caller sent
     //                            in that CLI's own config object.
-    //   'claude-settings-file' — claude alone, whose model is written to
-    //                            <case>/.claude/settings.local.json rather than passed as
-    //                            a flag, so the app-wide default applies here.
+    //   'claude-settings-file' — claude alone, whose persistent model is written to
+    //                            <case>/.claude/settings.local.json (`modelOverride`). A
+    //                            per-session `model` from the caller goes out as --model and
+    //                            wins; without one, the app-wide default applies.
     //   'none'                 — shell has no model; deepseek's is a composition entry in
     //                            the profile's config tree, not a session field
     //                            (docs/deepseek-integration.md). Both get nothing.
@@ -1087,7 +1097,7 @@ export function registerSessionRoutes(
             | string
             | undefined)
         : modelSource?.source === 'claude-settings-file'
-          ? modelConfig?.defaultModel || undefined
+          ? body.model || modelConfig?.defaultModel || undefined
           : undefined;
     const claudeModeConfig = await ctx.getClaudeModeConfig();
     // Section 6.3: force non-granted users to a classifier-guarded mode.

src/web/schemas.ts

@@ -528,6 +528,19 @@ export const CreateSessionSchema = z.object({
   effort: effortLevelSchema,
   /** Model override to write to .claude/settings.local.json (e.g., "opus[1m]"). Empty string clears. */
   modelOverride: z.string().max(50).optional(),
+  /**
+   * Claude model for THIS session only, passed as `claude --model <id>`; nothing is written to
+   * disk. Wins over the app-wide default model. Same character set as the registry's
+   * `model-claude` pattern, so a value accepted here is never rejected at launch. An empty
+   * string means no per-session model, as it does for `modelOverride`. Claude only: the route
+   * refuses it for any other CLI.
+   */
+  model: z
+    .string()
+    .max(100)
+    .regex(/^[a-zA-Z0-9._\-[\]]+$/)
+    .or(z.literal(''))
+    .optional(),
   openCodeConfig: OpenCodeConfigSchema,
   codexConfig: CodexConfigSchema,
   geminiConfig: GeminiConfigSchema,

src/web/server.ts

@@ -3520,6 +3520,7 @@ export class WebServer extends EventEmitter {
               ompConfig: muxSession.mode === 'omp' ? savedState?.ompConfig : undefined,
               envOverrides: savedEnvOverrides,
               effort: savedState?.effort,
+              model: savedState?.model,
               attachmentHistory: savedAttachmentHistory,
               // The pane's last Enter. Without it the response viewer would show
               // the launch conversation until the user types again, even though