diff --git a/packages/opencode/src/server/workspace.ts b/packages/opencode/src/server/workspace.ts
index 29b1ab9869..501ed0ab29 100644
--- a/packages/opencode/src/server/workspace.ts
+++ b/packages/opencode/src/server/workspace.ts
@@ -48,14 +48,14 @@ export function workspaceProxyURL(target: string | URL, requestURL: URL) {
   return proxyURL
 }
 
-async function getSessionWorkspace(url: URL) {
+async function getSession(url: URL) {
   const id = getWorkspaceRouteSessionID(url)
   if (!id) return null
 
   const session = await AppRuntime.runPromise(
     Session.Service.use((svc) => svc.get(id)).pipe(Effect.withSpan("WorkspaceRouter.lookup")),
   ).catch(() => undefined)
-  return session?.workspaceID
+  return session
 }
 
 export function WorkspaceRouterMiddleware(upgrade: UpgradeWebSocket): MiddlewareHandler {
@@ -64,10 +64,20 @@ export function WorkspaceRouterMiddleware(upgrade: UpgradeWebSocket): Middleware
   return async (c, next) => {
     const url = new URL(c.req.url)
 
-    const sessionWorkspaceID = await getSessionWorkspace(url)
-    const workspaceID = sessionWorkspaceID || url.searchParams.get("workspace")
+    const session = await getSession(url)
+    const workspaceID = session?.workspaceID || url.searchParams.get("workspace")
 
     if (!workspaceID || url.pathname.startsWith("/console") || Flag.OPENCODE_WORKSPACE_ID) {
+      if (session) {
+        return Instance.provide({
+          directory: session.directory,
+          init: () => AppRuntime.runPromise(InstanceBootstrap),
+          async fn() {
+            return next()
+          },
+        })
+      }
+
       return next()
     }
 
diff --git a/packages/opencode/test/server/session-routes-directory.test.ts b/packages/opencode/test/server/session-routes-directory.test.ts
new file mode 100644
index 0000000000..baaa55d237
--- /dev/null
+++ b/packages/opencode/test/server/session-routes-directory.test.ts
@@ -0,0 +1,130 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { Flag } from "@opencode-ai/core/flag/flag"
+import path from "path"
+import { GlobalBus, type GlobalEvent } from "../../src/bus/global"
+import { Instance } from "../../src/project/instance"
+import { Server } from "../../src/server/server"
+import * as Log from "@opencode-ai/core/util/log"
+import { resetDatabase } from "../fixture/db"
+import { tmpdir } from "../fixture/fixture"
+
+void Log.init({ print: false })
+
+const originalHttpApi = Flag.OPENCODE_EXPERIMENTAL_HTTPAPI
+type SyncTrace = { type: string; directory?: string }
+
+function app() {
+  Flag.OPENCODE_EXPERIMENTAL_HTTPAPI = false
+  return Server.Default().app
+}
+
+function route(pathname: string, directory: string, query?: Record<string, string>) {
+  const url = new URL(pathname, "http://localhost")
+  url.searchParams.set("directory", directory)
+  for (const [key, value] of Object.entries(query ?? {})) {
+    url.searchParams.set(key, value)
+  }
+  return url
+}
+
+async function fetchJson<T>(
+  pathname: string,
+  directory: string,
+  init?: RequestInit,
+  query?: Record<string, string>,
+) {
+  const response = await app().fetch(new Request(route(pathname, directory, query), init))
+  if (response.status !== 200) throw new Error(await response.text())
+  return (await response.json()) as T
+}
+
+function pathFor(pathname: string, params: Record<string, string>) {
+  return Object.entries(params).reduce((result, [key, value]) => result.replace(`:${key}`, value), pathname)
+}
+
+afterEach(async () => {
+  Flag.OPENCODE_EXPERIMENTAL_HTTPAPI = originalHttpApi
+  await Instance.disposeAll()
+  await resetDatabase()
+})
+
+describe("Hono session routes", () => {
+  test("use request directory for non-session routes and saved session directory for session routes", async () => {
+    await using sessionDir = await tmpdir({
+      git: true,
+      config: { formatter: false, lsp: false },
+      init: (dir) => Bun.write(path.join(dir, "marker.txt"), "session-directory"),
+    })
+    await using requestDir = await tmpdir({
+      git: true,
+      config: { formatter: false, lsp: false },
+      init: (dir) => Bun.write(path.join(dir, "marker.txt"), "request-directory"),
+    })
+
+    const json = { "content-type": "application/json" }
+    const trace: SyncTrace[] = []
+    const onEvent = (event: GlobalEvent) => {
+      if (event.payload.type !== "sync") return
+      if (!["session.created.1", "message.updated.1", "message.part.updated.1"].includes(event.payload.syncEvent.type)) return
+      trace.push({ type: event.payload.syncEvent.type, directory: event.directory })
+    }
+    GlobalBus.on("event", onEvent)
+
+    const session = await fetchJson<{ id: string }>("/session", sessionDir.path, {
+      method: "POST",
+      headers: json,
+      body: JSON.stringify({ title: "session-dir" }),
+    })
+
+    const currentPath = await fetchJson<{ directory: string }>("/path", requestDir.path)
+    expect(currentPath.directory).toBe(requestDir.path)
+
+    const marker = await fetchJson<{ type: string; content: string }>(
+      "/file/content",
+      requestDir.path,
+      undefined,
+      {
+        path: "marker.txt",
+      },
+    )
+    expect(marker).toMatchObject({ type: "text", content: "request-directory" })
+
+    await fetchJson<unknown>(pathFor("/session/:sessionID", { sessionID: session.id }), requestDir.path)
+
+    await fetchJson<unknown>(
+      pathFor("/session/:sessionID/fork", { sessionID: session.id }),
+      requestDir.path,
+      {
+        method: "POST",
+        headers: json,
+        body: JSON.stringify({}),
+      },
+    )
+
+    await fetchJson<{ info: { path: { cwd: string; root: string } }; parts: unknown[] }>(
+      pathFor("/session/:sessionID/shell", { sessionID: session.id }),
+      requestDir.path,
+      {
+        method: "POST",
+        headers: json,
+        body: JSON.stringify({
+          agent: "build",
+          model: { providerID: "test", modelID: "test" },
+          command: "pwd",
+        }),
+      },
+    )
+    GlobalBus.off("event", onEvent)
+
+    expect(trace).toContainEqual({ type: "session.created.1", directory: sessionDir.path })
+    expect(trace.filter((event) => event.type === "session.created.1")).toEqual([
+      { type: "session.created.1", directory: sessionDir.path },
+      { type: "session.created.1", directory: sessionDir.path },
+    ])
+    expect(trace.filter((event) => event.type === "message.updated.1").map((event) => event.directory)).toEqual(
+      expect.arrayContaining([sessionDir.path]),
+    )
+    expect(trace.filter((event) => event.type === "message.updated.1").every((event) => event.directory === sessionDir.path))
+      .toBe(true)
+  })
+})