Use Match for workbench dispatch

ts/EFFECT_NATIVE_REWRITE_AUDIT.md

@@ -1855,6 +1855,26 @@ Notes:
   - `cd ts && bun run lint`
   - `git diff --check`
 
+### 2026-06-04: Workbench Match Dispatch Slice
+
+- Status: migrated and root-verified.
+- Completed:
+  - `ts/packages/workbench/src/qa/mock-api.ts` now dispatches mock RPC
+    service requests with `effect/Match` and keeps the existing unknown-service
+    `{}` fallback.
+  - `ts/packages/workbench/src/atoms/workbench.ts` now dispatches chat submit
+    behavior for `graph-rag`, `document-rag`, and `agent` through
+    `Match.exhaustive` over the `ChatMode` union.
+  - The strict scan for native `switch` statements in `ts/packages` is clean:
+    `rg -n "\bswitch\s*\(" ts/packages --glob '*.ts' --glob '*.tsx'` returns
+    no matches.
+- Verification:
+  - `cd ts && bun run check:tsgo`
+  - `cd ts && bun run build`
+  - `cd ts && bun run test`
+  - `cd ts && bun run lint`
+  - `git diff --check`
+
 ## Subagent Findings To Preserve
 
 - MCP/workbench:
@@ -1982,6 +2002,9 @@ Notes:
   - ConfigService and KnowledgeCore operation dispatch now use `effect/Match`
     with `Match.exhaustive`; FlowManager and Librarian operation dispatch now
     use `effect/Match` with runtime-preserving `Match.orElse` fallbacks.
+  - Native `switch` statements are now clean in `ts/packages`; future branch
+    drift should keep service dispatch on `effect/Match` or Schema tagged-union
+    helpers.
   - Client RPC/BaseApi connection-state fanout now uses
     `effect/SubscriptionRef`; remaining gateway/client P1 work is broader API
     design, not listener bookkeeping.
@@ -2167,7 +2190,7 @@ Notes:
 ## Recommended PR Order
 
 1. MCP protocol parity tests and legacy stdio flip/removal decision.
-2. Flow/client RPC stream and remaining service operation `Match` follow-ups.
+2. Flow/client RPC stream API design beyond callback/Promise compatibility.
 3. Long-lived ref-backed `HashMap` state cleanup where clone helpers remain.
 4. Sibling service `Effect.fn` normalization where arrow-returned generators
    still appear.

ts/packages/workbench/src/atoms/workbench.ts

@@ -2,7 +2,7 @@ import { Clipboard as BrowserClipboard } from "@effect/platform-browser";
 import * as BrowserHttpClient from "@effect/platform-browser/BrowserHttpClient";
 import * as BrowserKeyValueStore from "@effect/platform-browser/BrowserKeyValueStore";
 import { BaseApi, type ConnectionState, type DocumentMetadata, type ExplainEvent, type StreamingMetadata, type Term, type Triple } from "@trustgraph/client";
-import { Cause, Clock, Context, Effect, Layer, Metric, Option, Random, Schema as S } from "effect";
+import { Cause, Clock, Context, Effect, Layer, Match, Metric, Option, Random, Schema as S } from "effect";
 import * as Otlp from "effect/unstable/observability/Otlp";
 import * as AsyncResult from "effect/unstable/reactivity/AsyncResult";
 import * as Atom from "effect/unstable/reactivity/Atom";
@@ -1576,14 +1576,14 @@ export const submitMessageAtom = commandAtom<{ input: string }, void>(
     explainEvents.push(event);
   };
 
-  switch (chatMode) {
+  Match.value(chatMode).pipe(
-    case "graph-rag":
+    Match.when("graph-rag", () => {
       flow.graphRagStreaming(trimmed, onChunk, onError, undefined, collection, onExplain);
-      break;
+    }),
-    case "document-rag":
+    Match.when("document-rag", () => {
       flow.documentRagStreaming(trimmed, onChunk, onError, undefined, collection, onExplain);
-      break;
+    }),
-    case "agent":
+    Match.when("agent", () => {
       flow.agent(
         trimmed,
         (chunk, complete) => {
@@ -1633,8 +1633,9 @@ export const submitMessageAtom = commandAtom<{ input: string }, void>(
         onExplain,
         collection,
       );
-      break;
+    }),
-  }
+    Match.exhaustive,
+  );
   }),
 );
 

ts/packages/workbench/src/qa/mock-api.ts

@@ -1,5 +1,5 @@
 import { makeBaseApiWithRpc, type BaseApi, type DocumentMetadata, type ProcessingMetadata, type StreamingMetadata, type Triple } from "@trustgraph/client";
-import { Clock, Effect, Option, Schema as S } from "effect";
+import { Clock, Effect, Match, Option, Schema as S } from "effect";
 
 type ConfigValues = Record<string, Record<string, unknown>>;
 
@@ -284,22 +284,15 @@ function addDocument(state: MockState, metadata: DocumentMetadata): DocumentMeta
 }
 
 function dispatchRequest(state: MockState, service: string, request: Record<string, unknown>, flow: string | undefined): unknown {
-  switch (service) {
+  return Match.value(service).pipe(
-    case "flow":
+    Match.when("flow", () => dispatchFlow(state, request)),
-      return dispatchFlow(state, request);
+    Match.when("config", () => dispatchConfig(state, request)),
-    case "config":
+    Match.when("librarian", () => dispatchLibrarian(state, request)),
-      return dispatchConfig(state, request);
+    Match.when("knowledge", () => dispatchKnowledge(state, request)),
-    case "librarian":
+    Match.when("collection-management", () => dispatchCollections(state, request)),
-      return dispatchLibrarian(state, request);
+    Match.when("triples", () => dispatchTriples(state, request, flow)),
-    case "knowledge":
+    Match.orElse(() => ({})),
-      return dispatchKnowledge(state, request);
+  );
-    case "collection-management":
-      return dispatchCollections(state, request);
-    case "triples":
-      return dispatchTriples(state, request, flow);
-    default:
-      return {};
-  }
 }
 
 function dispatchFlow(state: MockState, request: Record<string, unknown>): unknown {