refactor(process): split the process manager out of the bash executor

New process/ capability family: @deepseek-ai/dsh-process owns ctx.processes —
abstract ProcessManager.spawn(spec) over a fully-explicit ProcessSpawnSpec —
plus the shared DSH_* managed-environment and CollectedOutput vocabulary;
@deepseek-ai/dsh-process-local carries the former bash-local run.ts plumbing
(detached groups, tail-keep spill-backed output, credential scrub, kill
escalation, kill-and-join disposal) with no config of its own.

dsh-bash-local becomes a consumer: it keeps command defaulting, the fused
deadline timedOut/aborted classification, the model-friendly terminal env
(now merged through the ordinary env channel), and the [stderr]-marked
background read merge, and spawns through ctx.processes. Background-process
lifetime moves to the manager, so an executor reload no longer kills live
background work; a background spawn failure is injected once into the read
path instead of being buffered as fake stderr. dsh-bash re-exports the moved
vocabulary so bash consumers keep one import root; dsh-bash-sandbox only
redeclares the inherited inject.

Every composition loading a bash executor now loads dsh-process-local (CLI,
examples, python bundled runtime, create-sdk bash feature, inline test
configs).

examples/tui-agent/tests/fixtures/tui-scripted.cordis.yml

@@ -4,6 +4,10 @@
 - id: scripted-llm
   name: './tui-scripted-llm.ts'
 
+# Managed child-process groups for the bash executor (spawn/kill/output plumbing).
+- id: processes
+  name: '@deepseek-ai/dsh-process-local'
+
 - id: bash
   name: '@deepseek-ai/dsh-bash-local'
 

examples/tui-agent/tests/tui.snapshot.ts

@@ -8,6 +8,7 @@ import { scrubRequestHeaders } from '@deepseek-ai/dsh-acp-snapshot'
 import type { Agent } from '@deepseek-ai/dsh-agent'
 import * as AgentCore from '@deepseek-ai/dsh-agent-spine-demo'
 import { LocalBashExecutor } from '@deepseek-ai/dsh-bash-local'
+import LocalProcessManager from '@deepseek-ai/dsh-process-local'
 import WorkerCodeRuntime from '@deepseek-ai/dsh-code-runtime-worker'
 import CommandService from '@deepseek-ai/dsh-commands'
 import LocalFileSystem from '@deepseek-ai/dsh-fs-local'
@@ -204,6 +205,7 @@ async function mountScenarioContext(
     skills: { local: { agentsHome: join(cwd, '.agents') } },
   })
   await ctx.plugin(TokenMeterService)
+  await ctx.plugin(LocalProcessManager)
   await ctx.plugin(LocalBashExecutor, { cwd, timeoutMs: 30_000 })
   await ctx.plugin(SnapshotLocalFileSystem, { cwd: '/' })
   await ctx.plugin(FsPolicy)