fix(httpapi): expose v2 session not found (#28511)

packages/opencode/test/server/httpapi-exercise/index.ts

@@ -675,22 +675,14 @@ const scenarios: Scenario[] = [
       path: route("/api/session/{sessionID}/context", { sessionID: "ses_httpapi_missing" }),
       headers: ctx.headers(),
     }))
-    .json(200, array, "none"),
+    .json(404, object, "status"),
   http.protected
     .get("/api/session/{sessionID}/message", "v2.session.messages")
     .at((ctx) => ({
       path: route("/api/session/{sessionID}/message", { sessionID: "ses_httpapi_missing" }),
       headers: ctx.headers(),
     }))
-    .json(
-      200,
-      (body) => {
-        object(body)
-        array(body.items)
-        object(body.cursor)
-      },
-      "none",
-    ),
+    .json(404, object, "status"),
   http.protected
     .get("/api/session/{sessionID}/message", "v2.session.messages.params")
     .at((ctx) => ({
@@ -700,15 +692,7 @@ const scenarios: Scenario[] = [
       })}`,
       headers: ctx.headers(),
     }))
-    .json(
-      200,
-      (body) => {
-        object(body)
-        array(body.items)
-        object(body.cursor)
-      },
-      "none",
-    ),
+    .json(404, object, "status"),
   http.protected
     .get("/api/session/{sessionID}/message", "v2.session.messages.cursor")
     .at((ctx) => ({
@@ -719,15 +703,7 @@ const scenarios: Scenario[] = [
       })}`,
       headers: ctx.headers(),
     }))
-    .json(
-      200,
-      (body) => {
-        object(body)
-        array(body.items)
-        object(body.cursor)
-      },
-      "none",
-    ),
+    .json(404, object, "status"),
   http.protected
     .get("/api/session/{sessionID}/message", "v2.session.messages.cursor.invalid")
     .at((ctx) => ({
@@ -752,14 +728,14 @@ const scenarios: Scenario[] = [
       path: route("/api/session/{sessionID}/compact", { sessionID: "ses_httpapi_missing" }),
       headers: ctx.headers(),
     }))
-    .status(204, undefined, "none"),
+    .status(404, undefined, "status"),
   http.protected
     .post("/api/session/{sessionID}/wait", "v2.session.wait")
     .at((ctx) => ({
       path: route("/api/session/{sessionID}/wait", { sessionID: "ses_httpapi_missing" }),
       headers: ctx.headers(),
     }))
-    .status(204, undefined, "none"),
+    .status(404, undefined, "status"),
   http.protected
     .get("/session", "session.list")
     .seeded((ctx) => ctx.session({ title: "List me" }))

packages/opencode/test/server/httpapi-public-openapi.test.ts

@@ -99,4 +99,20 @@ describe("PublicApi OpenAPI v2 errors", () => {
       "ServiceUnavailableError",
     )
   })
+
+  test("documents v2 session not-found errors", () => {
+    const spec = OpenApi.fromApi(PublicApi) as OpenApiSpec
+
+    for (const route of [
+      ["post", "/api/session/{sessionID}/prompt"],
+      ["post", "/api/session/{sessionID}/compact"],
+      ["post", "/api/session/{sessionID}/wait"],
+      ["get", "/api/session/{sessionID}/context"],
+      ["get", "/api/session/{sessionID}/message"],
+    ] as const) {
+      expect(componentName(responseRef(spec.paths[route[1]]?.[route[0]]?.responses?.["404"]) ?? "")).toBe(
+        "SessionNotFoundError",
+      )
+    }
+  })
 })

packages/opencode/test/server/httpapi-session.test.ts

@@ -402,6 +402,46 @@ describe("session HttpApi", () => {
     { git: true, config: { formatter: false, lsp: false } },
   )
 
+  it.instance(
+    "returns v2 public not found errors for missing sessions",
+    () =>
+      Effect.gen(function* () {
+        const test = yield* TestInstance
+        const headers = { "x-opencode-directory": test.directory }
+        const missing = SessionID.descending()
+        const expected = {
+          _tag: "SessionNotFoundError",
+          sessionID: missing,
+          message: `Session not found: ${missing}`,
+        }
+
+        const messages = yield* request(`/api/session/${missing}/message`, { headers })
+        expect(messages.status).toBe(404)
+        expect(yield* responseJson(messages)).toEqual(expected)
+
+        const context = yield* request(`/api/session/${missing}/context`, { headers })
+        expect(context.status).toBe(404)
+        expect(yield* responseJson(context)).toEqual(expected)
+
+        const compact = yield* request(`/api/session/${missing}/compact`, { method: "POST", headers })
+        expect(compact.status).toBe(404)
+        expect(yield* responseJson(compact)).toEqual(expected)
+
+        const wait = yield* request(`/api/session/${missing}/wait`, { method: "POST", headers })
+        expect(wait.status).toBe(404)
+        expect(yield* responseJson(wait)).toEqual(expected)
+
+        const prompt = yield* request(`/api/session/${missing}/prompt`, {
+          method: "POST",
+          headers: { ...headers, "content-type": "application/json" },
+          body: JSON.stringify({ prompt: { text: "hello" } }),
+        })
+        expect(prompt.status).toBe(404)
+        expect(yield* responseJson(prompt)).toEqual(expected)
+      }),
+    { git: true, config: { formatter: false, lsp: false } },
+  )
+
   it.instance(
     "serves sessions with migrated summary diffs missing file details",
     () =>