feat(local-model): the coding agent is chosen per session, with Pi and DeepSeek Harness

An installed model knew one coding agent: the one it was installed with.
The launch check never asked about the agent, only about the endpoint
and the model, so nothing stopped a second one. What was missing is the
list, and a way to get an agent that is not on the Mac yet.

The install view gains `harnesses`: every catalogue harness the model in
use can be run with, each with how it stands (`ready`, `installable`,
`installing`, `setup-needed`), the literal install command, a readiness
mark for scripts, and the actions the server accepts for it. `cli` stays
the default agent, and names one that can be started whenever one can,
so a client that reads only `cli` never starts an agent that is gone.

`POST /api/local-model/agent { cli }` installs one more agent beside an
installed model. It is not a job and not an event of the reducer: the
state stays `installed` whatever the installer does, so a failed npm
install never blocks a session on a model that works. Same install slot
and same compiled stock command as the `agent` step, one at a time, the
outcome in memory only.

The catalogue:
- `pi` is no longer gated. Its two open questions were answered by a run
  against a real model (the `name:tag` id reaches the runtime unchanged;
  its first request is 2,096 tokens), and Codeman now passes it the
  window. Its minimum is 65536 like the others: nothing below was run,
  and no model row offers less, so no Mac's pick changes.
- `deepseek` is new. It is a launcher: its install command leaves it
  with nothing to launch, so it is never reported installable (read off
  `discovery.launcherProfile`, not the id) and a Mac is offered it only
  where it was already set up. Its tool round trip was seen on a
  scripted endpoint only; the header says how to gate it again.
- a row may carry `readyMark`; `opencode` has the measured one.

A switch no longer refuses for the agent a model was checked with when
another agent that can run it is on the Mac.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

src/web/public/i18n.js

@@ -1628,8 +1628,8 @@
       '此 Mac 目前只使用 {model}。请先在本地模型窗口中切换模型。',
     'This model is not one of the checked models on this Mac.': '该模型不在此 Mac 上已检查的模型之列。',
     'This model is not on this Mac.': '此 Mac 上没有这个模型。',
-    '{cli} is not installed on this Mac. Install this model again to choose a coding agent.':
-      '此 Mac 上没有安装 {cli}。请重新安装此模型，以便选择编程智能体。',
+    '{cli} is not installed on this Mac. Install a coding agent in the local model window first.':
+      '此 Mac 上没有安装 {cli}。请先在本地模型窗口中安装一个编程智能体。',
     '{model} could not be deleted from this Mac.': '无法从此 Mac 删除 {model}。',
     // What the endpoint routes answer for the record of the model on this Mac (shown as a toast).
     'This endpoint belongs to the model Codeman runs on this Mac. Change or remove it in the local model window.':

src/web/routes/local-model-routes.ts

@@ -12,6 +12,7 @@
  * | `POST /api/local-model/runtime`  | `LocalModelRuntimeRequest`  | the install view; 409                          |
  * | `DELETE /api/local-model`        | `LocalModelRemoveRequest`   | the install view; 409                          |
  * | `DELETE /api/local-model/models` | `LocalModelDeleteRequest`   | the install view; 400, 409, 500                |
+ * | `POST /api/local-model/agent`    | `LocalModelAgentRequest`    | the install view; 400, 409                     |
  *
  * The GET is built from the hardware probe, the catalogue, the harness facts and the pure
  * `recommend()`, plus the `install` object of the install service
@@ -55,6 +56,10 @@
  *  - `DELETE /api/local-model/models` takes a model NAME in its body, never a path: the schema
  *    admits only `name:tag`, and the service deletes only a name of its own listing, through
  *    the runtime.
+ *  - `POST /api/local-model/agent` installs one more coding agent beside an installed model.
+ *    Its body names a CLI id only: the service takes it only when it is a row of the view's
+ *    `harnesses` that offers `install`, and runs the compiled stock command, never text from
+ *    the request. It looks at no session: nothing about the model in use changes.
  *  - Every dependency is injected (`LocalModelRouteDeps`), so a route test spawns nothing and
  *    does not need a Mac: it passes its own hardware, harness facts and service.
  */
@@ -97,6 +102,7 @@ import {
 } from '../../local-model/install-job.js';
 import { recommend } from '../../local-model/recommend.js';
 import {
+  LocalModelAgentSchema,
   LocalModelDeleteSchema,
   LocalModelInstallSchema,
   LocalModelRemoveSchema,
@@ -261,7 +267,7 @@ export function registerLocalModelRoutes(
         // The measured budget once the runtime reported it, and the runtime download that an
         // install would still add: what turns the estimate into the figures of the consent.
         const options = await service.recommendOptions();
-        const install = await service.view();
+        const install = await service.view({ harnessFacts });
         // A row that is already a checked model on this Mac says so: choosing it is a switch.
         const recommendation = markLibraryCandidates(
           resolved.recommend(hardware, catalog, harnessFacts, options),
@@ -334,4 +340,11 @@ export function registerLocalModelRoutes(
     const body = parseBody(LocalModelDeleteSchema, req.body);
     return runVerb(reply, () => resolved.service().deleteLibraryModel(body, actorOf(req)));
   });
+
+  app.post('/api/local-model/agent', async (req, reply): Promise<LocalModelVerbResponse> => {
+    const denied = adminOnly(req, reply);
+    if (denied) return denied;
+    const body = parseBody(LocalModelAgentSchema, req.body);
+    return runVerb(reply, () => resolved.service().installAgent(body, actorOf(req)));
+  });
 }

src/web/schemas.ts

@@ -2481,14 +2481,20 @@ const localModelId = z
   .max(200)
   .regex(/^[a-z0-9][a-z0-9._-]*:[a-z0-9][a-z0-9._-]*$/, 'Invalid model id');
 
+/**
+ * A coding agent as a CLI registry id. A request-shape check only: the real gate is the
+ * service's own lookup of the id among the catalogue harnesses it offers right now.
+ */
+const localModelCli = z
+  .string()
+  .max(64)
+  .regex(/^[a-z0-9][a-z0-9_-]*$/, 'Invalid coding agent id');
+
 /** POST /api/local-model/install: the row the person chose and the size they confirmed. */
 export const LocalModelInstallSchema = z
   .object({
     modelId: localModelId,
-    cli: z
-      .string()
-      .max(64)
-      .regex(/^[a-z0-9][a-z0-9_-]*$/, 'Invalid coding agent id'),
+    cli: localModelCli,
     context: z.number().int().positive().max(MAX_DISCOVERED_CONTEXT_TOKENS),
     acknowledgedBytes: z.number().int().nonnegative().max(Number.MAX_SAFE_INTEGER),
   })
@@ -2511,6 +2517,9 @@ export const LocalModelUseSchema = z.object({ modelId: localModelId }).strict();
 /** DELETE /api/local-model/models: one model of the store, by its name. Never a path. */
 export const LocalModelDeleteSchema = z.object({ modelId: localModelId }).strict();
 
+/** POST /api/local-model/agent: one more coding agent to install beside an installed model. */
+export const LocalModelAgentSchema = z.object({ cli: localModelCli }).strict();
+
 /**
  * A shell-safe bare word, mirroring `config/cli-registry/schema.ts`'s own `shellToken` —
  * duplicated rather than imported, since the REAL safety boundary for anything built from