fix(pwsh): close the remaining review threads

- scrubbedParentEnv folds case before the DSH_ prefix check (Windows env
  names are case-insensitive; a parent dsh_* entry read back as \*
  in the child) and the service spec pins the lowercase probe.
- The acp.snapshot.ts pwsh probe follows resolvePwshPath() like the package
  suites, so a Windows host with only an install-location pwsh still runs
  the scenario.
- pwsh-tool-turn is re-recorded around [Console]::Out.Write('PWSH_OK'):
  the fixture carries no platform newline, so one recording replays on
  Windows and POSIX alike (record + refresh; replay-verified keyless).
- The pwsh-local Known Limitations bullet drops the self-defeating no-op
  advice: & { } is scoped to param(...), using/#requires scripts run from a
  file (both languages, pairing re-recorded).
- The capability-seams graph moves ctx.bashEnv ownership to bash-env and
  lists pwsh-local/tool-pwsh on the ctx.bash seam (source updated,
  docs regenerated).
- The tool-bash presenter fixture retires the stale 'command aborted'
  literal for the shipped 'tool call aborted' message.

packages/subprocess/subprocess/src/index.ts

@@ -45,7 +45,10 @@ export const SENSITIVE_ENV_PATTERN = /KEY|PASSWORD|SECRET|TOKEN/i
  * `HOME`, locale, and proxy variables survive, so child CLIs run normally;
  * harness identity never leaks implicitly (a deliberately forwarded
  * credential or current `DSH_*` fact goes through the spec's explicit `env`,
- * which merges after this scrub). Exported as a plain function so spawners
+ * which merges after this scrub). Both scrubs match case-insensitively:
+ * Windows environment names are case-insensitive, so a parent `dsh_*` entry
+ * would otherwise survive and read back as `$env:DSH_*` in the child;
+ * deliberate lowercase `dsh_*` names on POSIX are implausible. Exported as a plain function so spawners
  * that cannot route through the service (node-pty backends, SDK-managed
  * transports) share the one scrub definition.
  * @returns a fresh environment object safe to hand to a child spawn.
@@ -53,7 +56,7 @@ export const SENSITIVE_ENV_PATTERN = /KEY|PASSWORD|SECRET|TOKEN/i
 export function scrubbedParentEnv(): Record<string, string> {
   const env: Record<string, string> = {}
   for (const [key, value] of Object.entries(process.env)) {
-    if (value !== undefined && !SENSITIVE_ENV_PATTERN.test(key) && !key.startsWith(DSH_ENV_PREFIX)) env[key] = value
+    if (value !== undefined && !SENSITIVE_ENV_PATTERN.test(key) && !key.toUpperCase().startsWith(DSH_ENV_PREFIX)) env[key] = value
   }
   return env
 }

packages/subprocess/subprocess/tests/service.spec.ts

@@ -52,20 +52,23 @@ describe('SubprocessService seam', () => {
     await expect(ctx.plugin(SecondService)).rejects.toThrow(/service "subprocess" has been registered/)
   })
 
-  it('scrubbedParentEnv drops credential-shaped and DSH_ names but keeps PATH', () => {
+  it('scrubbedParentEnv drops credential-shaped and DSH_ names (case-insensitively) but keeps PATH', () => {
     process.env.DSH_SCRUB_PROBE = 'stale'
+    process.env.dsh_scrub_probe_lower = 'stale'
     process.env.SCRUB_PROBE_TOKEN = 'secret'
     process.env.SCRUB_PROBE_PASSWORD = 'secret'
     process.env.SCRUB_PROBE_PLAIN = 'visible'
     try {
       const env = scrubbedParentEnv()
       expect(env.DSH_SCRUB_PROBE).toBeUndefined()
+      expect(env.dsh_scrub_probe_lower).toBeUndefined()
       expect(env.SCRUB_PROBE_TOKEN).toBeUndefined()
       expect(env.SCRUB_PROBE_PASSWORD).toBeUndefined()
       expect(env.SCRUB_PROBE_PLAIN).toBe('visible')
       expect(env.PATH).toBeDefined()
     } finally {
       delete process.env.DSH_SCRUB_PROBE
+      delete process.env.dsh_scrub_probe_lower
       delete process.env.SCRUB_PROBE_TOKEN
       delete process.env.SCRUB_PROBE_PASSWORD
       delete process.env.SCRUB_PROBE_PLAIN