chore: delete dead modules, exports, fixtures, scripts, and unused dependencies (#654)

* chore: delete dead modules, exports, fixtures, scripts, and unused dependencies

* Keep mcp-app-json snapshot helpers now that the bridge imports them

Author: ScriptedAlchemy

.changeset/ponytail-dead-code.md

@@ -0,0 +1,6 @@
+---
+"agent-bundle": patch
+"@agent-bundle/runtime": patch
+---
+
+Drop the unused `open` dependency from `agent-bundle` and remove internal helpers that no package entry point exported and no code reached (the MCP App sandbox bridge, `durable-fs` pinned-file readers, unused Effect boundary helpers, `boundRenderEventStream`). Installs get one fewer package; no exported API changes. (#654)

agent-patterns/effect-errors.md

@@ -105,7 +105,7 @@ Callers of `runPromise` see the same types they see today.
 - Swallowing interruption as a typed success. Cancellation is `AbortError`.
   `Stream.toReadableStream`'s `Cause.squash` is not that mapping — use the
   boundary helper.
-- `Effect.runPromise` in a test to "see the error" when `runPromiseExit` +
+- `Effect.runPromise` in a test to "see the error" when `Effect.exit` +
   `Cause` is the assertion you want — still only through the boundary.
 - New public error codes without updating the authoring docs and the mapping
   table in `docs/effect-conventions.md`.