feat(source-control-ai): support OMP generation (#20624)

* feat(source-control-ai): support OMP text generation

Read prompts on stdin, retain OMP configured model by default, and reuse JSON model discovery.

Co-authored-by: unknown <1784931579@qq.com>

* test(source-control-ai): cover OMP large input and model overrides

* fix(omp): keep configured model default out of discovered catalog

* fix(omp): hide config default from model discovery catalog

* fix(omp): separate terminal discovery from generation defaults

* test(omp): keep model probe import compatible with CLI typecheck

* test: align Source Control AI registry contracts with OMP

---------

Co-authored-by: unknown <1784931579@qq.com>

src/shared/commit-message-agent-spec.ts

@@ -1,3 +1,4 @@
+import { OMP_MODEL_LIST_ARGS, parseOmpModelList } from './omp-model-list-probe'
 import type { TuiAgent } from './tui-agent'
 import { isTuiAgentEnabled } from './tui-agent-selection'
 import { labelFromModelId } from './model-id-label'
@@ -88,6 +89,29 @@ export type CommitMessageAgentCapability = {
 }
 
 export const COMMIT_MESSAGE_AGENT_SPECS: Partial<Record<TuiAgent, CommitMessageAgentSpec>> = {
+  omp: {
+    id: 'omp',
+    label: 'OMP',
+    binary: 'omp',
+    promptDelivery: 'stdin',
+    buildArgs: ({ model, thinkingLevel }) => [
+      '--print',
+      '--no-session',
+      '--no-tools',
+      '--no-extensions',
+      '--no-skills',
+      '--no-rules',
+      '--mode',
+      'text',
+      ...(model && model !== 'default' ? ['--model', model] : []),
+      ...(thinkingLevel ? ['--thinking', thinkingLevel] : [])
+    ],
+    singletonOptions: [['--model'], ['--thinking']],
+    modelSource: 'dynamic',
+    modelDiscovery: { binary: 'omp', args: OMP_MODEL_LIST_ARGS, parse: parseOmpModelList },
+    models: [{ id: 'default', label: 'Config default' }],
+    defaultModelId: 'default'
+  },
   ...buildPrimaryCommitMessageAgentSpecs({
     CLAUDE_THINKING_LEVELS,
     OPENAI_THINKING_LEVELS,