Improve ACPX adapter configuration (#5290)

## Thinking Path

> - Paperclip orchestrates AI agents across several adapter
implementations.
> - ACPX is a local adapter path that can proxy Claude and Codex-style
execution.
> - Its configuration needed stronger schema defaults, provider-aware
model handling, and better UI support.
> - Plugin authors also need clear docs for managed resources.
> - This pull request improves ACPX adapter configuration and documents
plugin-managed resources.
> - The benefit is a more predictable adapter setup path without
changing unrelated control-plane behavior.

## What Changed

- Improved ACPX config schema, execution config handling, UI build
config, and route coverage.
- Added ACPX model filtering support and tests.
- Updated the agent config form and storybook coverage for ACPX
model/provider behavior.
- Expanded plugin authoring documentation for managed resources.

## Verification

- `pnpm install --frozen-lockfile`
- `pnpm exec vitest run server/src/__tests__/acpx-local-execute.test.ts
server/src/__tests__/adapter-routes.test.ts
ui/src/lib/acpx-model-filter.test.ts`

## Risks

- Low-to-medium risk: adapter configuration behavior changes can affect
ACPX users, but the change is isolated to ACPX/plugin-doc surfaces and
covered by targeted adapter tests.

## Model Used

- OpenAI GPT-5 Codex via Paperclip `codex_local` adapter, with
shell/git/GitHub CLI tool use.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

packages/adapters/acpx-local/src/server/config-schema.ts

@@ -1,10 +1,9 @@
 import type { AdapterConfigSchema } from "@paperclipai/adapter-utils";
 import {
   DEFAULT_ACPX_LOCAL_AGENT,
-  DEFAULT_ACPX_LOCAL_MODE,
   DEFAULT_ACPX_LOCAL_NON_INTERACTIVE_PERMISSIONS,
-  DEFAULT_ACPX_LOCAL_PERMISSION_MODE,
   DEFAULT_ACPX_LOCAL_TIMEOUT_SEC,
+  DEFAULT_ACPX_LOCAL_WARM_HANDLE_IDLE_MS,
   acpxAgentOptions,
 } from "../index.js";
 
@@ -26,27 +25,6 @@ export function getConfigSchema(): AdapterConfigSchema {
         type: "text",
         hint: "Required for custom agents; optional override for built-in Claude or Codex ACP commands.",
       },
-      {
-        key: "mode",
-        label: "Session mode",
-        type: "select",
-        default: DEFAULT_ACPX_LOCAL_MODE,
-        options: [
-          { value: "persistent", label: "Persistent" },
-          { value: "oneshot", label: "One shot" },
-        ],
-      },
-      {
-        key: "permissionMode",
-        label: "Permission mode",
-        type: "select",
-        default: DEFAULT_ACPX_LOCAL_PERMISSION_MODE,
-        options: [
-          { value: "approve-all", label: "Approve all" },
-          { value: "default", label: "Approve reads" },
-        ],
-        hint: "Defaults to maximum permissions. Approve reads grants read-only requests and asks for approval on writes.",
-      },
       {
         key: "nonInteractivePermissions",
         label: "Non-interactive permissions",
@@ -56,6 +34,7 @@ export function getConfigSchema(): AdapterConfigSchema {
           { value: "deny", label: "Deny" },
           { value: "fail", label: "Fail" },
         ],
+        hint: "Fallback if the ACP agent asks for input outside an interactive session. Paperclip still auto-approves permissions by default.",
       },
       {
         key: "cwd",
@@ -70,20 +49,12 @@ export function getConfigSchema(): AdapterConfigSchema {
         hint: "Optional ACPX session state directory. Defaults to Paperclip-managed company/agent scoped storage.",
       },
       {
-        key: "instructionsFilePath",
-        label: "Instructions file",
-        type: "text",
-        hint: "Optional absolute path to markdown instructions injected into the run prompt.",
-      },
-      {
-        key: "promptTemplate",
-        label: "Prompt template",
-        type: "textarea",
-      },
-      {
-        key: "bootstrapPromptTemplate",
-        label: "Bootstrap prompt template",
-        type: "textarea",
+        key: "fastMode",
+        label: "Codex fast mode",
+        type: "toggle",
+        default: false,
+        hint: "Only applies when ACP agent is Codex. Requests Codex Fast mode through ACP session config.",
+        meta: { visibleWhen: { key: "agent", values: ["codex"] } },
       },
       {
         key: "timeoutSec",
@@ -91,6 +62,13 @@ export function getConfigSchema(): AdapterConfigSchema {
         type: "number",
         default: DEFAULT_ACPX_LOCAL_TIMEOUT_SEC,
       },
+      {
+        key: "warmHandleIdleMs",
+        label: "Warm process idle ms",
+        type: "number",
+        default: DEFAULT_ACPX_LOCAL_WARM_HANDLE_IDLE_MS,
+        hint: "Defaults to 0, which closes the ACPX process after each run while retaining persistent session state.",
+      },
       {
         key: "env",
         label: "Environment JSON",