Speed up inbound WebSocket validation (#1895)

* perf(protocol): generate inbound ws validators

* perf(client): use generated ws validation

* docs(protocol): document generated validation

* fix(protocol): make validator generation source-only

* test(protocol): cover explicit provider model normalization

* fix(protocol): preserve inbound compat defaults

* fix(protocol): make validator import rewrite portable

* fix(protocol): harden validation safety checks

* fix(protocol): guard generated validator boundaries

* fix(protocol): normalize legacy inbound defaults

* fix(protocol): simplify generated validation safety net

* fix(protocol): keep cold typecheck source-only

* fix(protocol): encapsulate validator codegen

* fix(protocol): bootstrap source-alias typechecks

* fix(app): keep source aliases out of bundler config

* fix(protocol): harden validator codegen packaging

* fix(protocol): own zod-aot patches in generator

* fix(protocol): trim validator safety net

* fix(client): normalize provider updates before dispatch

* fix(protocol): keep validator generation out of install

CLAUDE.md

@@ -40,6 +40,7 @@ At the start of non-trivial work, list `docs/` and skim anything relevant to the
 | [docs/service-proxy.md](docs/service-proxy.md)                     | Service proxy: exposing workspace scripts at public URLs, DNS setup, reverse proxy config                                      |
 | [docs/development.md](docs/development.md)                         | Dev server, build sync gotchas, CLI reference, agent state, Playwright MCP                                                     |
 | [docs/rpc-namespacing.md](docs/rpc-namespacing.md)                 | WebSocket RPC naming convention — dotted namespaces and `.request`/`.response` pairs                                           |
+| [docs/protocol-validation.md](docs/protocol-validation.md)         | zod-aot generated inbound WebSocket validation, patched compiler regressions, schema-purity rules                              |
 | [docs/terminal-performance.md](docs/terminal-performance.md)       | Terminal latency pipeline, coalescing/backpressure invariants, benchmark + perf spec usage                                     |
 | [docs/testing.md](docs/testing.md)                                 | TDD workflow, determinism, real dependencies over mocks, test organization                                                     |
 | [docs/mobile-testing.md](docs/mobile-testing.md)                   | Maestro and mobile test workflows                                                                                              |
@@ -92,10 +93,13 @@ See [docs/development.md](docs/development.md) for full setup, build sync requir
   - `npm run format:files -- CLAUDE.md packages/app/src/components/message.tsx`
 - **The protocol stays backward-compatible. Features don't have to.** Two separate contracts:
   - **Protocol contract (always):** schema changes must not break parsing in either direction. An old client must still parse messages from a new daemon; a new daemon must still parse messages from an old client.
-    - New fields: `.optional()` with a sensible default or `.transform()` fallback.
+    - New fields: `.optional()` with a sensible default.
     - Never flip optional → required, remove fields, or narrow types (`string` → `enum`, `nullable` → non-null).
     - Removed fields stay accepted (we stop sending them, not stop reading them).
     - Test with: "does a 6-month-old client still parse this?" and "does a 6-month-old daemon still send something this client accepts?"
+    - Wire schemas are pure structural declarations. Do not add `.transform()`, `.catch()`, or `.preprocess()` to WebSocket message schemas; put normalization in an explicit post-validation pass.
+    - Plain `z.union()` is forbidden when every branch has a shared literal tag. Use `z.discriminatedUnion()` unless generated-code regression tests prove that specific shape is miscompiled.
+    - `.default()` is acceptable on primitive leaves only. Never put defaults on item schemas for large arrays or big inbound containers.
   - **Feature contract (per-feature):** a new feature may require a new daemon capability. The client detects whether the capability is present and either runs the feature or shows "Update the host to use this." That's it.
     - **No fallback paths.** Don't write a degraded version of a new feature that runs on old daemons. Don't fan out across legacy RPCs to simulate a missing capability. The user upgrades or doesn't get the feature.
     - **No defensive branches scattered through the feature.** Capability detection happens in one place; downstream code reads a clean shape.