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feat(web): compose a web session's agent from a named preset

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`session.create` takes an optional `agentPreset`, and the host resolves it,
mounts it during pre-publication setup, and records the resolved id on the
session header so a later resume rebuilds the same agent.

Resolution happens BEFORE the session exists, not inside setup: the session
boundary snapshots `meta` before asynchronous setup begins, so an id discovered
during setup could never reach the header. Mounting still happens in setup,
where a failure rolls the whole creation back rather than publishing a session
whose capabilities are half-installed.

Resume ignores whatever the request names and rebuilds from the stored id. A
resumed session's history was produced under that composition; restoring a
different one would replay tool calls the model can no longer make.

`dsh-agent-presets` now throws `UnknownPresetError` / `PresetMountError` so
the host can tell a bad request from a broken preset — they become
`agent-preset-not-found` and `agent-preset-invalid`.

Ships the two built-in compositions (`standard`, `core-web`) and the persona
row that lets them differ in identity. Nothing mounts them yet: no roster is
configured, so `composeAgent` finds no service and every session keeps the host
composition. Wiring the roster and moving base's agent-plane rows behind it is
the next commit, so the switch happens atomically with a real-composition test.
This commit is contained in:
Yichen Jiang
2026-08-03 22:38:11 +08:00
parent 739042a804
commit 91b55b9245
22 changed files with 458 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
packages/host/apiproxy/src/api/rpc.schema.ts
View File

@@ -46,6 +46,8 @@ export const rpcErrorSchema: z.ZodType<RpcError> = z.discriminatedUnion('code',
z.object({ code: z.literal('directory-exists'), message: z.string(), details: z.object({ path: z.string() }) }),
z.object({ code: z.literal('directory-create-failed'), message: z.string(), details: z.object({ path: z.string() }) }),
z.object({ code: z.literal('directory-picker-unavailable'), message: z.string(), details: z.object({ capability: z.string() }) }),
z.object({ code: z.literal('agent-preset-not-found'), message: z.string(), details: z.object({ agentPreset: z.string(), available: z.array(z.string()) }) }),
z.object({ code: z.literal('agent-preset-invalid'), message: z.string(), details: z.object({ agentPreset: z.string(), reason: z.string() }) }),
z.object({ code: z.literal('agent-busy'), message: z.string(), details: z.object({ reason: z.string() }) }),
z.object({ code: z.literal('queue-item-not-found'), message: z.string(), details: z.object({ itemId: z.string() }) }),
z.object({ code: z.literal('steer-unavailable'), message: z.string(), details: z.object({ itemId: z.string() }) }),

2
packages/host/apiproxy/src/api/rpc.ts
View File

@@ -44,6 +44,8 @@ export interface RpcErrorDetailsMap {
'directory-exists': { path: string }
'directory-create-failed': { path: string }
'directory-picker-unavailable': { capability: string }
'agent-preset-not-found': { agentPreset: string; available: string[] }
'agent-preset-invalid': { agentPreset: string; reason: string }
'agent-busy': { reason: string }
'queue-item-not-found': { itemId: MessageId }
'steer-unavailable': { itemId: MessageId }

1
packages/host/apiproxy/src/api/sessions.schema.ts
View File

@@ -100,6 +100,7 @@ export const sessionCreateRequestSchema = z.object({
workspaceId: workspaceIdSchema.optional(),
cwd: z.string().optional(),
sessionId: sessionIdSchema.optional(),
agentPreset: z.string().optional(),
}).refine(
payload => payload.workspaceId === undefined || payload.cwd === undefined,
{ message: 'session.create accepts workspaceId or cwd, not both' },

8
packages/host/apiproxy/src/api/sessions.ts
View File

@@ -199,8 +199,14 @@ export interface SessionsApi {
* session, while a different cwd fails with `session-conflict`. Workspace
* creation attaches the session after publication; an attach failure
* returns `workspace-attach-failed` with the published session id.
*
* `agentPreset` names the composition the new session's agent is built
* from; omitted, the deployment's default preset applies. The resolved id
* is stored on the session header, so a later resume rebuilds the same
* agent. An unknown id fails with `agent-preset-not-found`, and a preset
* whose composition cannot be mounted fails with `agent-preset-invalid`.
*/
create(request: RpcRequest<{ workspaceId?: WorkspaceId; cwd?: string; sessionId?: SessionId }>):
create(request: RpcRequest<{ workspaceId?: WorkspaceId; cwd?: string; sessionId?: SessionId; agentPreset?: string }>):
Promise<RpcResponse<{ sessionId: SessionId }>>
/**