diff --git a/packages/opencode/config.json b/packages/opencode/config.json
new file mode 100644
index 0000000000..c3eb6a56fa
--- /dev/null
+++ b/packages/opencode/config.json
@@ -0,0 +1,3 @@
+{
+  "$schema": "https://opencode.ai/config.json"
+}
\ No newline at end of file
diff --git a/packages/opencode/test/server/httpapi-exercise/index.ts b/packages/opencode/test/server/httpapi-exercise/index.ts
index 8cacb47132..2911521b2d 100644
--- a/packages/opencode/test/server/httpapi-exercise/index.ts
+++ b/packages/opencode/test/server/httpapi-exercise/index.ts
@@ -1260,6 +1260,47 @@ const scenarios: Scenario[] = [
     .probe({ path: "/global/upgrade", body: { target: 1 } })
     .at(() => ({ path: "/global/upgrade", body: { target: 1 } }))
     .status(400),
+
+  // ─── SDK routing-params drift coverage (replaces httpapi-query-schema-drift.test.ts) ───
+  // Each routing-aware GET endpoint runs through the real SDK client, which
+  // auto-injects `?directory=...&workspace=...`. Pre-#26581 these all 4xx'd
+  // because the typed query schemas didn't accept the SDK's injected fields.
+  // Any future endpoint added under WorkspaceRoutingMiddleware that forgets
+  // WorkspaceRoutingQueryFields will fail its `.viaSdk(...)` scenario on
+  // first run.
+  http.protected
+    .get("/session", "session.list.via_sdk")
+    .viaSdk((sdk) => sdk.session.list({ roots: true }, { throwOnError: true }))
+    .json(200, array, "status"),
+  http.protected
+    .get("/session/{sessionID}/message", "session.messages.via_sdk")
+    .at((ctx) => ({ path: route("/session/{sessionID}/message", { sessionID: "ses_via_sdk_drift" }), headers: ctx.headers() }))
+    .viaSdk((sdk) => sdk.session.messages({ sessionID: "ses_via_sdk_drift", limit: 80 }))
+    .status(404, undefined, "status"),
+  http.protected
+    .get("/find/file", "find.files.via_sdk")
+    .viaSdk((sdk) => sdk.find.files({ query: "foo" }, { throwOnError: true }))
+    .json(200, array, "status"),
+  http.protected
+    .get("/find", "find.text.via_sdk")
+    .viaSdk((sdk) => sdk.find.text({ pattern: "foo" }, { throwOnError: true }))
+    .json(200, array, "status"),
+  http.protected
+    .get("/file/content", "file.read.via_sdk")
+    .viaSdk((sdk) => sdk.file.read({ path: "foo" }, { throwOnError: true }))
+    .json(200, undefined, "status"),
+  http.protected
+    .get("/experimental/session", "experimental.session.list.via_sdk")
+    .viaSdk((sdk) => sdk.experimental.session.list({}, { throwOnError: true }))
+    .json(200, array, "status"),
+  http.protected
+    .get("/experimental/tool", "experimental.tool.list.via_sdk")
+    .viaSdk((sdk) => sdk.tool.list({ provider: "anthropic", model: "claude" }, { throwOnError: true }))
+    .json(200, array, "status"),
+  http.protected
+    .get("/vcs/diff", "vcs.diff.via_sdk")
+    .viaSdk((sdk) => sdk.vcs.diff({ mode: "git" }, { throwOnError: true }))
+    .json(200, array, "status"),
 ]
 
 const llmScenarios = new Set([
diff --git a/packages/opencode/test/server/httpapi-query-schema-drift.test.ts b/packages/opencode/test/server/httpapi-query-schema-drift.test.ts
deleted file mode 100644
index 68daeca1e9..0000000000
--- a/packages/opencode/test/server/httpapi-query-schema-drift.test.ts
+++ /dev/null
@@ -1,134 +0,0 @@
-import { afterEach, describe, expect } from "bun:test"
-import { Effect } from "effect"
-import { Flag } from "@opencode-ai/core/flag/flag"
-import { Server } from "../../src/server/server"
-import { SessionID } from "../../src/session/schema"
-import { resetDatabase } from "../fixture/db"
-import { disposeAllInstances, tmpdir } from "../fixture/fixture"
-import { it } from "../lib/effect"
-
-const originalWorkspaces = Flag.OPENCODE_EXPERIMENTAL_WORKSPACES
-
-function app() {
-  return Server.Default().app
-}
-
-function request(url: string, init?: RequestInit) {
-  return Effect.promise(async () => app().request(url, init))
-}
-
-function withTmp<A, E, R>(
-  options: Parameters<typeof tmpdir>[0],
-  fn: (tmp: Awaited<ReturnType<typeof tmpdir>>) => Effect.Effect<A, E, R>,
-) {
-  return Effect.acquireRelease(
-    Effect.promise(() => tmpdir(options)),
-    (tmp) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-  ).pipe(Effect.flatMap(fn))
-}
-
-afterEach(async () => {
-  Flag.OPENCODE_EXPERIMENTAL_WORKSPACES = originalWorkspaces
-  await disposeAllInstances()
-  await resetDatabase()
-})
-
-// Regression for the "OpenAPI advertises ?directory&workspace, runtime
-// rejects them" drift class. Each affected route must accept both params
-// without 400.
-describe("httpapi query schema drift", () => {
-  const routingParams = (dir: string) =>
-    `directory=${encodeURIComponent(dir)}&workspace=${encodeURIComponent("ws_test")}`
-
-  const expectNotSchemaRejection = (status: number, url: string) => {
-    expect(status, `route ${url} 400'd, query schema is missing routing fields`).not.toBe(400)
-  }
-
-  it.live(
-    "session list accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/session?${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "session messages accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/session/${SessionID.descending()}/message?limit=80&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "file find/file accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/find/file?query=foo&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "file find/text accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/find?pattern=foo&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "file read accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/file?path=foo&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "experimental session list accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/experimental/session?${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "experimental tool list accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/experimental/tool?provider=anthropic&model=claude&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-
-  it.live(
-    "vcs diff accepts directory and workspace",
-    withTmp({ config: { formatter: false, lsp: false } }, (tmp) =>
-      Effect.gen(function* () {
-        const url = `/vcs/diff?mode=working&${routingParams(tmp.path)}`
-        const response = yield* request(url)
-        expectNotSchemaRejection(response.status, url)
-      }),
-    ),
-  )
-})