fix(server): generate durable thread titles

apps/server/src/textGeneration/ClaudeTextGeneration.test.ts

@@ -264,7 +264,7 @@ it.layer(ClaudeTextGenerationTestLayer)("ClaudeTextGeneration", (it) => {
               '  "Reconnect failures after restart because the session state does not recover"  ',
           },
         }),
-        stdinMustContain: "You write concise thread titles for coding conversations.",
+        stdinMustContain: "Please investigate reconnect failures after restarting the session.",
       },
       (textGeneration) =>
         Effect.gen(function* () {

apps/server/src/textGeneration/CodexTextGeneration.ts

@@ -7,15 +7,19 @@ import * as Scope from "effect/Scope";
 import * as Stream from "effect/Stream";
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
-import { type CodexSettings, type ModelSelection } from "@t3tools/contracts";
+import {
+  type CodexSettings,
+  DEFAULT_TEXT_GENERATION_REASONING_EFFORT,
+  type ModelSelection,
+  TextGenerationError,
+} from "@t3tools/contracts";
 import { sanitizeBranchFragment, sanitizeFeatureBranchName } from "@t3tools/shared/git";
 import { resolveSpawnCommand } from "@t3tools/shared/shell";
 
 import { resolveAttachmentPath } from "../attachmentStore.ts";
 import * as ServerConfig from "../config.ts";
 import { expandHomePath } from "../pathExpansion.ts";
 import { codexExecLaunchArgs, resolveCodexLaunchArgs } from "../provider/Layers/codexLaunchArgs.ts";
-import { TextGenerationError } from "@t3tools/contracts";
 import * as TextGeneration from "./TextGeneration.ts";
 import {
   buildBranchNamePrompt,
@@ -33,7 +37,6 @@ import {
 import { getModelSelectionStringOptionValue } from "@t3tools/shared/model";
 import { getCodexServiceTierOptionValue } from "../codexModelOptions.ts";
 
-const CODEX_GIT_TEXT_GENERATION_REASONING_EFFORT = "low";
 const CODEX_TIMEOUT_MS = 180_000;
 const encodeJsonString = Schema.encodeEffect(Schema.fromJsonString(Schema.Unknown));
 /**
@@ -178,7 +181,7 @@ export const makeCodexTextGeneration = Effect.fn("makeCodexTextGeneration")(func
       const launchArgs = resolveCodexLaunchArgs(codexConfig.launchArgs, resolvedEnvironment);
       const reasoningEffort =
         getModelSelectionStringOptionValue(modelSelection, "reasoningEffort") ??
-        CODEX_GIT_TEXT_GENERATION_REASONING_EFFORT;
+        DEFAULT_TEXT_GENERATION_REASONING_EFFORT;
       const serviceTier = getCodexServiceTierOptionValue(modelSelection);
       const spawnCommand = yield* resolveSpawnCommand(
         codexConfig.binaryPath || "codex",

apps/server/src/textGeneration/TextGenerationPrompts.test.ts

@@ -154,6 +154,18 @@ describe("buildThreadTitlePrompt", () => {
     expect(result.prompt).toContain("User message:");
     expect(result.prompt).toContain("Investigate reconnect regressions after session restore");
     expect(result.prompt).not.toContain("Attachment metadata:");
+    expect(result.prompt).toContain(
+      "Generate a title that will help the user recognize this T3 Code thread weeks later.",
+    );
+    expect(result.prompt).toContain(
+      "Title the subject and outcome. Discard incidental instructions.",
+    );
+    expect(result.prompt).toContain(
+      "Name the product change, not the mock, plan, report, branch, or PR used to produce it.",
+    );
+    expect(result.prompt).not.toContain(
+      "Title should summarize the user's request, not restate it verbatim.",
+    );
   });
 
   it("includes attachment metadata when attachments are provided", () => {
@@ -183,12 +195,11 @@ describe("buildThreadTitlePrompt", () => {
     });
 
     expect(result.prompt).toContain(
-      "The user requested a new title based on the contents of this thread.",
+      "Generate a new title that will help the user recognize this T3 Code thread weeks later.",
     );
     expect(result.prompt).toContain('The previous title was "Investigate reconnect regressions".');
-    expect(result.prompt).toContain("better represents the current state of the thread");
     expect(result.prompt).toContain(
-      "Capture the thread's intent, not a PR number or other superficial detail.",
+      "Capture the current durable subject and outcome across the whole thread, not merely its initial request or latest step.",
     );
     expect(result.prompt).toContain("Thread contents:");
     expect(result.prompt).toContain("The remaining issue is stale session state");

apps/server/src/textGeneration/TextGenerationPrompts.ts

@@ -150,6 +150,8 @@ export interface BranchNamePromptInput {
 interface PromptFromMessageInput {
   instruction: string;
   responseShape: string;
+  guidance?: ReadonlyArray<string> | undefined;
+  rulesLabel?: string | undefined;
   rules: ReadonlyArray<string>;
   message: string;
   messageLabel?: string | undefined;
@@ -177,7 +179,8 @@ function buildPromptFromMessage(input: PromptFromMessageInput): string {
   const promptSections = [
     input.instruction,
     input.responseShape,
-    "Rules:",
+    ...(input.guidance ?? []),
+    input.rulesLabel ?? "Rules:",
     ...input.rules.map((rule) => `- ${rule}`),
     "",
     `${input.messageLabel ?? "User message"}:`,
@@ -234,26 +237,41 @@ export function buildThreadTitlePrompt(input: ThreadTitlePromptInput) {
   const prompt = buildPromptFromMessage({
     instruction: isRegeneration
       ? [
-          "You write concise thread titles for coding conversations.",
-          "The user requested a new title based on the contents of this thread.",
+          "Generate a new title that will help the user recognize this T3 Code thread weeks later.",
           `The previous title was ${JSON.stringify(input.previousTitle)}.`,
-          "Come up with a new title that better represents the current state of the thread.",
         ].join("\n")
-      : "You write concise thread titles for coding conversations.",
-    responseShape: "Return a JSON object with key: title.",
+      : "Generate a title that will help the user recognize this T3 Code thread weeks later.",
+    responseShape: "Return JSON with exactly one key: title.",
+    guidance: [
+      "",
+      "Before answering, silently reduce the request to:",
+      "- Subject: What system, feature, or problem is this really about?",
+      "- Outcome: What does the user ultimately want to understand or change?",
+      "- Incidental instructions: What only describes how the agent should do the work?",
+      "",
+      "Title the subject and outcome. Discard incidental instructions.",
+      "",
+    ],
+    rulesLabel: "Editorial rules:",
     rules: [
-      isRegeneration
-        ? "Title should summarize the thread's current state, not just its initial request."
-        : "Title should summarize the user's request, not restate it verbatim.",
+      "3-8 words, fewer than 40 characters.",
+      "Use a compact noun phrase or clear action phrase.",
+      "Capture the umbrella goal when the request lists several symptoms or steps.",
+      "Name the product change, not the mock, plan, report, branch, or PR used to produce it.",
+      "Models, subagents, tools, output formats, and monitoring instructions do not belong in the title unless they are themselves the topic.",
+      'For reviews, name what is being reviewed and the relevant concern. Avoid generic titles such as "Review PR 123" when linked or attached context reveals the subject.',
+      "For research, name the question domain rather than the requested research process.",
+      "Do not claim the work is complete.",
+      "Do not copy and truncate the user's message.",
+      "Avoid project names already visible in the UI, quotes, labels, filler, and trailing punctuation.",
+      "Use attached images as primary context for UI issues.",
+      "When a URL or attachment is the only source of the subject, use available tools to inspect it. If it cannot be resolved, remain accurate rather than guessing.",
       ...(isRegeneration
         ? [
-            "Capture the thread's intent, not a PR number or other superficial detail.",
+            "Capture the current durable subject and outcome across the whole thread, not merely its initial request or latest step.",
             "Return a different title from the previous title.",
           ]
         : []),
-      "Keep it short and specific (3-8 words).",
-      "Avoid quotes, filler, prefixes, and trailing punctuation.",
-      "If images are attached, use them as primary context for visual/UI issues.",
     ],
     message: input.message,
     ...(isRegeneration

packages/contracts/src/model.ts

@@ -145,6 +145,7 @@ export const PREFERRED_DEFAULT_CODEX_MODELS: ReadonlyArray<string> = [
   "gpt-5.6-terra",
 ];
 export const DEFAULT_TEXT_GENERATION_MODEL = "gpt-5.6-luna";
+export const DEFAULT_TEXT_GENERATION_REASONING_EFFORT = "low";
 
 export const DEFAULT_MODEL_BY_PROVIDER: Partial<Record<ProviderDriverKind, string>> = {
   [CODEX_DRIVER_KIND]: DEFAULT_MODEL,

packages/contracts/src/settings.test.ts

@@ -112,6 +112,14 @@ describe("ClientSettings sidebar v2", () => {
 });
 
 describe("ServerSettings.providerInstances (slice-2 invariant)", () => {
+  it("defaults text generation to Luna at low reasoning effort", () => {
+    expect(DEFAULT_SERVER_SETTINGS.textGenerationModelSelection).toEqual({
+      instanceId: ProviderInstanceId.make("codex"),
+      model: "gpt-5.6-luna",
+      options: [{ id: "reasoningEffort", value: "low" }],
+    });
+  });
+
   it("defaults to an empty record so legacy configs without the key still decode", () => {
     expect(DEFAULT_SERVER_SETTINGS.providerInstances).toEqual({});
   });

packages/contracts/src/settings.ts

@@ -3,7 +3,11 @@ import * as Duration from "effect/Duration";
 import * as Schema from "effect/Schema";
 import * as SchemaTransformation from "effect/SchemaTransformation";
 import { TrimmedNonEmptyString, TrimmedString } from "./baseSchemas.ts";
-import { DEFAULT_TEXT_GENERATION_MODEL, ProviderOptionSelections } from "./model.ts";
+import {
+  DEFAULT_TEXT_GENERATION_MODEL,
+  DEFAULT_TEXT_GENERATION_REASONING_EFFORT,
+  ProviderOptionSelections,
+} from "./model.ts";
 import { ModelSelection } from "./orchestration.ts";
 import { ProviderInstanceConfig, ProviderInstanceId } from "./providerInstance.ts";
 
@@ -498,6 +502,12 @@ export const ServerSettings = Schema.Struct({
       Effect.succeed({
         instanceId: ProviderInstanceId.make("codex"),
         model: DEFAULT_TEXT_GENERATION_MODEL,
+        options: [
+          {
+            id: "reasoningEffort",
+            value: DEFAULT_TEXT_GENERATION_REASONING_EFFORT,
+          },
+        ],
       }),
     ),
   ),