diff --git a/apps/server/src/provider/ClaudeModelCatalog.test.ts b/apps/server/src/provider/ClaudeModelCatalog.test.ts
index d5c9d8f53d1e..3aa8d2abfcd0 100644
--- a/apps/server/src/provider/ClaudeModelCatalog.test.ts
+++ b/apps/server/src/provider/ClaudeModelCatalog.test.ts
@@ -5,8 +5,10 @@ import { hasValidClaudeManifestAdapters } from "./ClaudeModelManifest.ts";
 import type { ModelManifestData } from "./ModelManifest.ts";
 import {
   formatClaudeVersionUpgradeMessage,
+  getClaudeCatalogModelCapabilities,
   normalizeClaudeCatalogEffort,
   resolveClaudeCatalogApiModelId,
+  resolveClaudeCatalogContextWindowTokens,
   resolveClaudeCatalogEffort,
   resolveClaudeModelCatalog,
   resolveClaudeModelsForVersion,
@@ -80,7 +82,7 @@ describe("Claude model catalog", () => {
     );
   });
 
-  it("resolves aliases and declarative adapter mappings", () => {
+  it("resolves aliases without exposing provider-managed effort or context options", () => {
     const base = manifest();
     const input: ModelManifestData = {
       ...base,
@@ -107,12 +109,24 @@ describe("Claude model catalog", () => {
       "claude-synthetic-next",
     );
     assert.strictEqual(normalizeClaudeCatalogEffort(catalog, "extreme", "synthetic"), "high");
+    assert.deepStrictEqual(
+      getClaudeCatalogModelCapabilities(catalog, "synthetic").optionDescriptors,
+      [],
+    );
+    assert.strictEqual(resolveClaudeCatalogEffort(catalog, "synthetic", "extreme"), undefined);
     assert.strictEqual(
       resolveClaudeCatalogApiModelId(catalog, {
         instanceId: ProviderInstanceId.make("claudeAgent"),
         model: "synthetic",
       }),
-      "claude-synthetic-next[large]",
+      "claude-synthetic-next",
+    );
+    assert.strictEqual(
+      resolveClaudeCatalogContextWindowTokens(catalog, {
+        instanceId: ProviderInstanceId.make("claudeAgent"),
+        model: "synthetic",
+      }),
+      undefined,
     );
   });
 
@@ -137,7 +151,7 @@ describe("Claude model catalog", () => {
     assert.isFalse(hasValidClaudeManifestAdapters(malformed));
   });
 
-  it("appends custom models with their own descriptors and keeps bare slugs opaque", () => {
+  it("hides provider-managed options on custom models and keeps bare slugs opaque", () => {
     const catalog = scopeClaudeModelCatalog(resolveClaudeModelCatalog(manifest()), [
       "synthetic",
       {
@@ -163,15 +177,13 @@ describe("Claude model catalog", () => {
     assert.strictEqual(resolveClaudeModelSlug(catalog, "synthetic"), "synthetic");
     assert.strictEqual(resolveClaudeCatalogEffort(catalog, "synthetic", "extreme"), undefined);
 
-    // The entry with descriptors resolves user-defined effort ids and passes
-    // them through untouched (no effortMap, no model suffix).
     assert.strictEqual(
       resolveClaudeCatalogEffort(catalog, "claude-custom-tuned", "brutal"),
-      "brutal",
+      undefined,
     );
     assert.strictEqual(
       resolveClaudeCatalogEffort(catalog, "claude-custom-tuned", "bogus"),
-      "gentle",
+      undefined,
     );
     assert.strictEqual(
       normalizeClaudeCatalogEffort(catalog, "brutal", "claude-custom-tuned"),
diff --git a/apps/server/src/provider/ClaudeModelCatalog.ts b/apps/server/src/provider/ClaudeModelCatalog.ts
index e601e9dc9392..6203741a6af8 100644
--- a/apps/server/src/provider/ClaudeModelCatalog.ts
+++ b/apps/server/src/provider/ClaudeModelCatalog.ts
@@ -29,6 +29,18 @@ import {
 const CLAUDE = ProviderDriverKind.make("claudeAgent");
 const EMPTY_CAPABILITIES: ModelCapabilities = { optionDescriptors: [] };
 
+function useProviderConfiguredOptions(model: ServerProviderModel): ServerProviderModel {
+  const descriptors = model.capabilities?.optionDescriptors;
+  if (!descriptors) return model;
+  return {
+    ...model,
+    capabilities: {
+      ...model.capabilities,
+      optionDescriptors: descriptors.filter(({ id }) => id !== "effort" && id !== "contextWindow"),
+    },
+  };
+}
+
 export interface ClaudeCatalogModel {
   readonly model: ServerProviderModel;
   readonly runtime: ClaudeCodeProfile;
@@ -49,7 +61,7 @@ function tryResolveClaudeModelCatalog(manifest: ModelManifestData): ClaudeModelC
     const adapter = decodeClaudeModelAdapter(entry.adapter ?? {});
     if (Option.isNone(profile) || Option.isNone(adapter)) return null;
     models.push({
-      model: entry.model,
+      model: useProviderConfiguredOptions(entry.model),
       runtime: profile.value.claudeCode ?? {},
       compatibility: adapter.value.claudeCode ?? {},
     });
@@ -75,8 +87,8 @@ export const BUNDLED_CLAUDE_MODEL_CATALOG = resolveClaudeModelCatalog(BUNDLED_MO
  * Scope the catalog to one instance's settings: custom model slugs stay opaque
  * (a built-in alias they shadow is dropped, canonical slugs and capabilities
  * are preserved), and custom entries that declare their own capabilities are
- * appended so the adapter resolves effort / fast mode / thinking against the
- * user's descriptors instead of the empty default. Custom entries carry no
+ * appended so the adapter resolves fast mode / thinking against the user's
+ * descriptors instead of the empty default. Custom entries carry no
  * runtime profile, so option values pass through to Claude Code verbatim.
  */
 export function scopeClaudeModelCatalog(
@@ -104,12 +116,12 @@ export function scopeClaudeModelCatalog(
   for (const entry of customEntries) {
     if (!entry.capabilities || builtInSlugs.has(entry.slug)) continue;
     customCatalogModels.push({
-      model: {
+      model: useProviderConfiguredOptions({
         slug: entry.slug,
         name: entry.name,
         isCustom: true,
         capabilities: entry.capabilities,
-      },
+      }),
       runtime: {},
       compatibility: {},
     });
diff --git a/apps/server/src/provider/CodexDeveloperInstructions.ts b/apps/server/src/provider/CodexDeveloperInstructions.ts
index 6a7fee351bce..22010c3c9d89 100644
--- a/apps/server/src/provider/CodexDeveloperInstructions.ts
+++ b/apps/server/src/provider/CodexDeveloperInstructions.ts
@@ -194,7 +194,7 @@ ${browserToolInstructions(browserToolsAvailable)}
 
 export interface CodexRuntimeInfo {
   readonly model: string;
-  readonly reasoningEffort: string;
+  readonly reasoningEffort?: string;
 }
 
 export function buildCodexDeveloperInstructions(
diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
index ca596e6501cf..b5ac965309c6 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
@@ -39,6 +39,7 @@ import * as TestClock from "effect/testing/TestClock";
 import { attachmentRelativePath } from "../../attachmentStore.ts";
 import { ServerConfig } from "../../config.ts";
 import { ServerSettingsService } from "../../serverSettings.ts";
+import { BUNDLED_CLAUDE_MODEL_CATALOG, type ClaudeModelCatalog } from "../ClaudeModelCatalog.ts";
 import {
   SYNTHETIC_CLAUDE_CAPABLE_MODEL,
   SYNTHETIC_CLAUDE_COLLIDING_ALIAS,
@@ -167,6 +168,7 @@ function makeHarness(config?: {
   readonly cwd?: string;
   readonly baseDir?: string;
   readonly claudeConfig?: Partial<ClaudeSettings>;
+  readonly modelCatalog?: ClaudeModelCatalog;
   readonly instanceId?: ProviderInstanceId;
   readonly scopedLimitNames?: ClaudeAdapterLiveOptions["scopedLimitNames"];
   readonly environment?: ClaudeAdapterLiveOptions["environment"];
@@ -186,7 +188,7 @@ function makeHarness(config?: {
     ...(config?.environment ? { environment: config.environment } : {}),
     ...(config?.instanceId ? { instanceId: config.instanceId } : {}),
     ...(config?.scopedLimitNames ? { scopedLimitNames: config.scopedLimitNames } : {}),
-    modelCatalog: Effect.succeed(SYNTHETIC_CLAUDE_MODEL_CATALOG),
+    modelCatalog: Effect.succeed(config?.modelCatalog ?? SYNTHETIC_CLAUDE_MODEL_CATALOG),
     ...(config?.getSessionMessages ? { getSessionMessages: config.getSessionMessages } : {}),
     ...(config?.forkSession ? { forkSession: config.forkSession } : {}),
     createQuery: (input) => {
@@ -590,6 +592,37 @@ describe("ClaudeAdapterLive", () => {
     );
   });
 
+  it.effect("uses Claude settings for effort and context despite saved T3 choices", () => {
+    const harness = makeHarness({
+      modelCatalog: BUNDLED_CLAUDE_MODEL_CATALOG,
+      environment: { ...process.env, CLAUDE_CODE_DISABLE_1M_CONTEXT: "1" },
+    });
+    return Effect.gen(function* () {
+      const adapter = yield* ClaudeAdapter;
+      yield* adapter.startSession({
+        threadId: THREAD_ID,
+        provider: ProviderDriverKind.make("claudeAgent"),
+        modelSelection: createModelSelection(
+          ProviderInstanceId.make("claudeAgent"),
+          "claude-opus-5-5",
+          [
+            { id: "effort", value: "max" },
+            { id: "contextWindow", value: "1m" },
+          ],
+        ),
+        runtimeMode: "full-access",
+      });
+
+      const options = harness.getLastCreateQueryInput()?.options;
+      assert.equal(options?.model, "claude-opus-5-5");
+      assert.equal(options?.effort, undefined);
+      assert.equal(options?.env?.CLAUDE_CODE_DISABLE_1M_CONTEXT, "1");
+    }).pipe(
+      Effect.provideService(Random.Random, makeDeterministicRandomService()),
+      Effect.provide(harness.layer),
+    );
+  });
+
   it.effect("runs Claude SDK sessions with the configured CLAUDE_CONFIG_DIR", () => {
     const harness = makeHarness({ claudeConfig: { homePath: "~/.claude-work" } });
     return Effect.gen(function* () {
diff --git a/apps/server/src/provider/Layers/CodexAdapter.test.ts b/apps/server/src/provider/Layers/CodexAdapter.test.ts
index 9f464bdaa177..19f15b7c1635 100644
--- a/apps/server/src/provider/Layers/CodexAdapter.test.ts
+++ b/apps/server/src/provider/Layers/CodexAdapter.test.ts
@@ -415,7 +415,7 @@ sessionErrorLayer("CodexAdapterLive session errors", (it) => {
     }),
   );
 
-  it.effect("maps codex model options before sending a turn", () =>
+  it.effect("keeps Codex effort in config while mapping service tier", () =>
     Effect.gen(function* () {
       const adapter = yield* CodexAdapter;
       yield* adapter.startSession({
@@ -442,7 +442,6 @@ sessionErrorLayer("CodexAdapterLive session errors", (it) => {
       NodeAssert.deepStrictEqual(runtime.sendTurnImpl.mock.calls[0]?.[0], {
         input: "hello",
         model: "gpt-5.3-codex",
-        effort: "high",
         serviceTier: "priority",
       });
     }),
@@ -608,7 +607,6 @@ sessionErrorLayer("CodexAdapterLive session errors", (it) => {
       NodeAssert.deepStrictEqual(runtime.sendTurnImpl.mock.calls[0]?.[0], {
         input: "hello",
         model: "gpt-5.3-codex",
-        effort: "high",
         serviceTier: "flex",
       });
     }).pipe(Effect.provide(customLayer));
diff --git a/apps/server/src/provider/Layers/CodexAdapter.ts b/apps/server/src/provider/Layers/CodexAdapter.ts
index 0ecc9693ab04..551bd6e1b8e4 100644
--- a/apps/server/src/provider/Layers/CodexAdapter.ts
+++ b/apps/server/src/provider/Layers/CodexAdapter.ts
@@ -44,7 +44,6 @@ import { ChildProcessSpawner } from "effect/unstable/process";
 import * as CodexErrors from "effect-codex-app-server/errors";
 import * as EffectCodexSchema from "effect-codex-app-server/schema";
 
-import { getModelSelectionStringOptionValue } from "@t3tools/shared/model";
 import { getCodexServiceTierOptionValue } from "../../codexModelOptions.ts";
 import * as McpProviderSession from "../../mcp/McpProviderSession.ts";
 
@@ -2527,10 +2526,6 @@ export const makeCodexAdapter = Effect.fn("makeCodexAdapter")(function* (
     );
 
     const session = yield* requireSession(input.threadId);
-    const reasoningEffort =
-      input.modelSelection?.instanceId === boundInstanceId
-        ? getModelSelectionStringOptionValue(input.modelSelection, "reasoningEffort")
-        : undefined;
     const serviceTier =
       input.modelSelection?.instanceId === boundInstanceId
         ? getCodexServiceTierOptionValue(input.modelSelection)
@@ -2541,11 +2536,6 @@ export const makeCodexAdapter = Effect.fn("makeCodexAdapter")(function* (
         ...(input.modelSelection?.instanceId === boundInstanceId
           ? { model: input.modelSelection.model }
           : {}),
-        ...(reasoningEffort
-          ? {
-              effort: reasoningEffort as EffectCodexSchema.V2TurnStartParams__ReasoningEffort,
-            }
-          : {}),
         ...(serviceTier ? { serviceTier } : {}),
         ...(input.interactionMode !== undefined ? { interactionMode: input.interactionMode } : {}),
         ...(codexAttachments.length > 0 ? { attachments: codexAttachments } : {}),
diff --git a/apps/server/src/provider/Layers/CodexCollabRuntime.integration.test.ts b/apps/server/src/provider/Layers/CodexCollabRuntime.integration.test.ts
index 2a9fb56c186a..cdc3b4636947 100644
--- a/apps/server/src/provider/Layers/CodexCollabRuntime.integration.test.ts
+++ b/apps/server/src/provider/Layers/CodexCollabRuntime.integration.test.ts
@@ -14,7 +14,12 @@ import * as NodePath from "node:path";
 
 import * as NodeServices from "@effect/platform-node/NodeServices";
 import { it } from "@effect/vitest";
-import { type ProviderApprovalDecision, type ProviderEvent, ThreadId } from "@t3tools/contracts";
+import {
+  type ProviderApprovalDecision,
+  type ProviderEvent,
+  ThreadId,
+  TurnId,
+} from "@t3tools/contracts";
 import * as Deferred from "effect/Deferred";
 import * as Effect from "effect/Effect";
 import * as Fiber from "effect/Fiber";
@@ -741,7 +746,7 @@ describe("CodexSessionRuntime collab integration", () => {
       yield* runtime.start();
       yield* runtime.sendTurn({ input: "keep working" });
       yield* runtime.sendTurn({ input: "queued follow-up" });
-      yield* runtime.interruptTurn();
+      yield* runtime.interruptTurn(TurnId.make(queuedTurnId));
 
       const interrupts = NodeFS.readFileSync(interruptsPath, "utf8")
         .trim()
diff --git a/apps/server/src/provider/Layers/CodexProvider.test.ts b/apps/server/src/provider/Layers/CodexProvider.test.ts
index 0c7a40d9bd9e..f1c4266dfa10 100644
--- a/apps/server/src/provider/Layers/CodexProvider.test.ts
+++ b/apps/server/src/provider/Layers/CodexProvider.test.ts
@@ -2,7 +2,7 @@ import { assert, it } from "@effect/vitest";
 
 import { applyPreferredCodexDefaultModel, mapCodexModelCapabilities } from "./CodexProvider.ts";
 
-it("maps current Codex model capability fields", () => {
+it("exposes service tiers while leaving reasoning effort to Codex config", () => {
   const capabilities = mapCodexModelCapabilities({
     additionalSpeedTiers: [],
     defaultReasoningEffort: "super-high",
@@ -34,13 +34,6 @@ it("maps current Codex model capability fields", () => {
   });
 
   assert.deepStrictEqual(capabilities.optionDescriptors, [
-    {
-      id: "reasoningEffort",
-      label: "Reasoning",
-      type: "select",
-      options: [{ id: "super-high", label: "super-high", isDefault: true }],
-      currentValue: "super-high",
-    },
     {
       id: "serviceTier",
       label: "Service Tier",
diff --git a/apps/server/src/provider/Layers/CodexProvider.ts b/apps/server/src/provider/Layers/CodexProvider.ts
index cdf40f73b1bd..6fa204c41c28 100644
--- a/apps/server/src/provider/Layers/CodexProvider.ts
+++ b/apps/server/src/provider/Layers/CodexProvider.ts
@@ -77,23 +77,8 @@ export interface CodexAppServerProviderSnapshot {
   readonly skills: ReadonlyArray<ServerProviderSkill>;
 }
 
-const REASONING_EFFORT_LABELS: Readonly<Record<string, string>> = {
-  none: "None",
-  minimal: "Minimal",
-  low: "Low",
-  medium: "Medium",
-  high: "High",
-  xhigh: "Extra High",
-  max: "Max",
-  ultra: "Ultra",
-};
-
 const DEFAULT_SERVICE_TIER_ID = "default";
 
-function reasoningEffortLabel(reasoningEffort: string): string {
-  return REASONING_EFFORT_LABELS[reasoningEffort] ?? reasoningEffort;
-}
-
 function codexAccountAuthLabel(account: CodexSchema.V2GetAccountResponse["account"]) {
   if (!account) return undefined;
   if (account.type === "apiKey") return "OpenAI API Key";
@@ -145,20 +130,6 @@ function codexAccountEmail(account: CodexSchema.V2GetAccountResponse["account"])
 export function mapCodexModelCapabilities(
   model: CodexSchema.V2ModelListResponse__Model,
 ): ModelCapabilities {
-  const reasoningOptions = model.supportedReasoningEfforts.map(({ reasoningEffort }) =>
-    reasoningEffort ===
-    (codexModelFamily(model.model) === "gpt-6-astra" ? "medium" : model.defaultReasoningEffort)
-      ? {
-          id: reasoningEffort,
-          label: reasoningEffortLabel(reasoningEffort),
-          isDefault: true,
-        }
-      : {
-          id: reasoningEffort,
-          label: reasoningEffortLabel(reasoningEffort),
-        },
-  );
-  const defaultReasoning = reasoningOptions.find((option) => option.isDefault)?.id;
   const serviceTiers =
     model.serviceTiers && model.serviceTiers.length > 0
       ? model.serviceTiers
@@ -175,15 +146,6 @@ export function mapCodexModelCapabilities(
   const defaultServiceTier = catalogDefaultServiceTier ?? DEFAULT_SERVICE_TIER_ID;
   const optionDescriptors: ProviderOptionDescriptor[] = [];
 
-  if (reasoningOptions.length > 0) {
-    optionDescriptors.push({
-      id: "reasoningEffort",
-      label: "Reasoning",
-      type: "select",
-      options: reasoningOptions,
-      ...(defaultReasoning ? { currentValue: defaultReasoning } : {}),
-    });
-  }
   if (serviceTiers.length > 0) {
     optionDescriptors.push({
       id: "serviceTier",
diff --git a/apps/server/src/provider/Layers/CodexSessionRuntime.test.ts b/apps/server/src/provider/Layers/CodexSessionRuntime.test.ts
index ec113ab7c521..75675494f147 100644
--- a/apps/server/src/provider/Layers/CodexSessionRuntime.test.ts
+++ b/apps/server/src/provider/Layers/CodexSessionRuntime.test.ts
@@ -277,17 +277,15 @@ describe("buildTurnStartParams", () => {
         mode: "default",
         settings: {
           model: "gpt-5.3-codex",
-          reasoning_effort: "medium",
           developer_instructions: buildCodexDeveloperInstructions("default", {
             model: "gpt-5.3-codex",
-            reasoningEffort: "medium",
           }),
         },
       },
     });
   });
 
-  it("reports the same fallback model and effort in settings and instructions", () => {
+  it("leaves effort to Codex config when no override is given", () => {
     const params = Effect.runSync(
       buildTurnStartParams({
         threadId: "provider-thread-1",
@@ -299,8 +297,9 @@ describe("buildTurnStartParams", () => {
 
     const settings = params.collaborationMode?.settings;
     NodeAssert.equal(settings?.model, DEFAULT_MODEL);
-    NodeAssert.equal(settings?.reasoning_effort, "medium");
-    NodeAssert.ok(settings?.developer_instructions?.includes(`as ${DEFAULT_MODEL} with medium`));
+    NodeAssert.equal(settings?.reasoning_effort, undefined);
+    NodeAssert.ok(settings?.developer_instructions?.includes(`as ${DEFAULT_MODEL}`));
+    NodeAssert.ok(!settings?.developer_instructions?.includes("reasoning effort"));
   });
 
   it.effect("routes approvals to the auto reviewer in auto mode", () =>
diff --git a/apps/server/src/provider/Layers/CodexSessionRuntime.ts b/apps/server/src/provider/Layers/CodexSessionRuntime.ts
index 674d23327b65..120164c3e2f5 100644
--- a/apps/server/src/provider/Layers/CodexSessionRuntime.ts
+++ b/apps/server/src/provider/Layers/CodexSessionRuntime.ts
@@ -590,15 +590,14 @@ function buildCodexCollaborationMode(input: {
     return undefined;
   }
   const model = normalizeCodexModelSlug(input.model) ?? DEFAULT_MODEL;
-  const reasoningEffort = input.effort ?? "medium";
   return {
     mode: input.interactionMode,
     settings: {
       model,
-      reasoning_effort: reasoningEffort,
+      ...(input.effort ? { reasoning_effort: input.effort } : {}),
       developer_instructions: buildCodexDeveloperInstructions(
         input.interactionMode,
-        { model, reasoningEffort },
+        { model, ...(input.effort ? { reasoningEffort: input.effort } : {}) },
         input.browserToolsAvailable ?? true,
       ),
     },
@@ -2592,7 +2591,7 @@ export const makeCodexSessionRuntime = (
                 .pipe(Effect.timeoutOption("3 seconds"), Effect.ignore),
             { concurrency: 8, discard: true },
           ).pipe(Effect.timeoutOption("10 seconds"), Effect.ignore);
-          const effectiveTurnId = turnId ?? session.activeTurnId;
+          const effectiveTurnId = session.activeTurnId ?? turnId;
           if (!effectiveTurnId) {
             return;
           }
diff --git a/apps/server/src/textGeneration/CodexTextGeneration.test.ts b/apps/server/src/textGeneration/CodexTextGeneration.test.ts
index 91c9cb94b5d5..5142e7cfb7e5 100644
--- a/apps/server/src/textGeneration/CodexTextGeneration.test.ts
+++ b/apps/server/src/textGeneration/CodexTextGeneration.test.ts
@@ -32,7 +32,6 @@ interface FakeCodexInput {
   stderr?: string;
   requireImage?: boolean;
   requireServiceTier?: string;
-  requireReasoningEffort?: string;
   forbidReasoningEffort?: boolean;
   requireArg?: string;
   forbidArg?: string;
@@ -48,7 +47,6 @@ function makeFakeCodexBinary(dir: string, input: FakeCodexInput) {
   const check = JSON.stringify({
     requireImage: input.requireImage ?? false,
     requireServiceTier: input.requireServiceTier ?? null,
-    requireReasoningEffort: input.requireReasoningEffort ?? null,
     forbidReasoningEffort: input.forbidReasoningEffort ?? false,
     requireArg: input.requireArg ?? null,
     forbidArg: input.forbidArg ?? null,
@@ -106,12 +104,6 @@ function makeFakeCodexBinary(dir: string, input: FakeCodexInput) {
         ") {",
         '  fail("unexpected service tier config: " + seenServiceTier, 5);',
         "}",
-        "if (",
-        "  check.requireReasoningEffort !== null &&",
-        '  seenReasoningEffort !== `model_reasoning_effort="${check.requireReasoningEffort}"`',
-        ") {",
-        '  fail("unexpected reasoning effort config: " + seenReasoningEffort, 6);',
-        "}",
         "if (check.forbidReasoningEffort && seenReasoningEffort.length > 0) {",
         '  fail("reasoning effort config should be omitted: " + seenReasoningEffort, 7);',
         "}",
@@ -209,31 +201,29 @@ it.layer(CodexTextGenerationTestLayer)("CodexTextGeneration", (it) => {
     ),
   );
 
-  it.effect(
-    "forwards codex service tier and non-default reasoning effort into codex exec config",
-    () =>
-      withFakeCodexEnv(
-        {
-          output: JSON.stringify({
-            subject: "Add important change",
-            body: "",
-          }),
-          requireServiceTier: "priority",
-          requireReasoningEffort: "xhigh",
-          stdinMustNotContain: "branch must be a short semantic git branch fragment",
-        },
-        (textGeneration) =>
-          textGeneration.generateCommitMessage({
-            cwd: process.cwd(),
-            branch: "feature/codex-effect",
-            stagedSummary: "M README.md",
-            stagedPatch: "diff --git a/README.md b/README.md",
-            modelSelection: createModelSelection(ProviderInstanceId.make("codex"), "gpt-5.4", [
-              { id: "reasoningEffort", value: "xhigh" },
-              { id: "serviceTier", value: "priority" },
-            ]),
-          }),
-      ),
+  it.effect("forwards Codex service tier but leaves effort to config", () =>
+    withFakeCodexEnv(
+      {
+        output: JSON.stringify({
+          subject: "Add important change",
+          body: "",
+        }),
+        requireServiceTier: "priority",
+        forbidReasoningEffort: true,
+        stdinMustNotContain: "branch must be a short semantic git branch fragment",
+      },
+      (textGeneration) =>
+        textGeneration.generateCommitMessage({
+          cwd: process.cwd(),
+          branch: "feature/codex-effect",
+          stagedSummary: "M README.md",
+          stagedPatch: "diff --git a/README.md b/README.md",
+          modelSelection: createModelSelection(ProviderInstanceId.make("codex"), "gpt-5.4", [
+            { id: "reasoningEffort", value: "xhigh" },
+            { id: "serviceTier", value: "priority" },
+          ]),
+        }),
+    ),
   );
 
   it.effect("passes exec-safe launch args into codex exec", () =>
@@ -281,14 +271,14 @@ it.layer(CodexTextGenerationTestLayer)("CodexTextGeneration", (it) => {
     ),
   );
 
-  it.effect("defaults git text generation codex effort to low", () =>
+  it.effect("leaves Git text generation effort to Codex config", () =>
     withFakeCodexEnv(
       {
         output: JSON.stringify({
           subject: "Add important change",
           body: "",
         }),
-        requireReasoningEffort: "low",
+        forbidReasoningEffort: true,
       },
       (textGeneration) =>
         textGeneration.generateCommitMessage({
diff --git a/apps/server/src/textGeneration/CodexTextGeneration.ts b/apps/server/src/textGeneration/CodexTextGeneration.ts
index 4c9ac59d8422..5f3991b371ad 100644
--- a/apps/server/src/textGeneration/CodexTextGeneration.ts
+++ b/apps/server/src/textGeneration/CodexTextGeneration.ts
@@ -9,7 +9,6 @@ import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
 import {
   type CodexSettings,
-  DEFAULT_TEXT_GENERATION_REASONING_EFFORT,
   type ModelSelection,
   type ServerProviderModel,
   TextGenerationError,
@@ -35,7 +34,7 @@ import {
   sanitizeThreadTitle,
   toJsonSchemaObject,
 } from "./TextGenerationUtils.ts";
-import { codexModelFamily, getModelSelectionStringOptionValue } from "@t3tools/shared/model";
+import { codexModelFamily } from "@t3tools/shared/model";
 import { getCodexServiceTierOptionValue } from "../codexModelOptions.ts";
 
 const CODEX_TIMEOUT_MS = 180_000;
@@ -189,9 +188,6 @@ export const makeCodexTextGeneration = Effect.fn("makeCodexTextGeneration")(func
         )?.slug ??
         requestedModel;
       const launchArgs = resolveCodexLaunchArgs(codexConfig.launchArgs, resolvedEnvironment);
-      const reasoningEffort =
-        getModelSelectionStringOptionValue(modelSelection, "reasoningEffort") ??
-        DEFAULT_TEXT_GENERATION_REASONING_EFFORT;
       const serviceTier = getCodexServiceTierOptionValue(modelSelection);
       const spawnCommand = yield* resolveSpawnCommand(
         codexConfig.binaryPath || "codex",
@@ -204,8 +200,6 @@ export const makeCodexTextGeneration = Effect.fn("makeCodexTextGeneration")(func
           "read-only",
           "--model",
           model,
-          "--config",
-          `model_reasoning_effort="${reasoningEffort}"`,
           ...(serviceTier ? ["--config", `service_tier="${serviceTier}"`] : []),
           "--output-schema",
           schemaPath,
diff --git a/docs/user/composer.md b/docs/user/composer.md
index 6e699d0669c1..ad2aa94fffea 100644
--- a/docs/user/composer.md
+++ b/docs/user/composer.md
@@ -69,7 +69,10 @@ T3 Code remembers your provider, model, and model options for new threads. A
 project's configured model takes precedence; resetting that project setting
 returns to the remembered selection.
 
-Leaving reasoning level or service tier unset uses the provider's own configuration.
+For Codex, set reasoning effort and context length in `~/.codex/config.toml`. For
+Claude Code, use `~/.claude/settings.json` for effort and its `env` settings for
+1M context support. T3 Code shows the context window reported by the provider.
+Leaving service tier unset uses the provider's configuration.
 
 ## Quote an assistant response
 
diff --git a/docs/user/keybindings.md b/docs/user/keybindings.md
index ad1b157bbb75..7f827cc06694 100644
--- a/docs/user/keybindings.md
+++ b/docs/user/keybindings.md
@@ -15,7 +15,7 @@ use `mod+Shift+Enter` for the opposite action. In a new thread, `mod+Enter` keep
 starting the thread in the background.
 
 Use `mod+shift+m` to choose a model and `mod+shift+h` to choose a host.
-Use `mod+shift+e` for effort, `mod+shift+a` for access mode, `mod+shift+x` for the
+Use `mod+shift+e` for available model traits, `mod+shift+a` for access mode, `mod+shift+x` for the
 workspace, and `mod+shift+g` for the Git branch. The workspace menu includes the
 current checkout, a new worktree, and the previous worktree when available.
 Use `mod+shift+l` to reuse the previous worktree directly.
diff --git a/docs/user/providers-claude.md b/docs/user/providers-claude.md
index cce194dbd2b4..dc748ab7873b 100644
--- a/docs/user/providers-claude.md
+++ b/docs/user/providers-claude.md
@@ -93,7 +93,7 @@ list, open that Claude instance in **Settings > Providers** and add its full mod
 ID with **Add custom model**. Then select it in the chat model picker.
 `ANTHROPIC_DEFAULT_*_MODEL` variables map Claude Code aliases such as `sonnet`; they
 do not replace the explicit model ID selected in T3 Code. Custom models may have
-fewer effort, thinking, or context controls than built-in models.
+fewer T3 Code controls than built-in models.
 
 Verify the model used in OpenRouter's activity dashboard. For current compatibility
 requirements, use the
diff --git a/packages/contracts/src/model.ts b/packages/contracts/src/model.ts
index 31e5f9d63305..b480e343e373 100644
--- a/packages/contracts/src/model.ts
+++ b/packages/contracts/src/model.ts
@@ -164,7 +164,6 @@ export const PREFERRED_DEFAULT_CODEX_MODELS: ReadonlyArray<string> = [
 export const DEFAULT_TEXT_GENERATION_MODEL = "gpt-6-luna";
 /** Keep the official Antigravity session's current model. Never send this ID to ACP. */
 export const ANTIGRAVITY_DEFAULT_MODEL = "antigravity-default";
-export const DEFAULT_TEXT_GENERATION_REASONING_EFFORT = "low";
 
 export const DEFAULT_MODEL_BY_PROVIDER: Partial<Record<ProviderDriverKind, string>> = {
   [CODEX_DRIVER_KIND]: DEFAULT_MODEL,
diff --git a/packages/contracts/src/settings.ts b/packages/contracts/src/settings.ts
index 3e301201910c..95a67712e82c 100644
--- a/packages/contracts/src/settings.ts
+++ b/packages/contracts/src/settings.ts
@@ -17,7 +17,6 @@ import { KeybindingShortcut } from "./keybindings.ts";
 import {
   CustomModelSetting,
   DEFAULT_TEXT_GENERATION_MODEL,
-  DEFAULT_TEXT_GENERATION_REASONING_EFFORT,
   ProviderOptionSelections,
 } from "./model.ts";
 import {
@@ -1227,12 +1226,7 @@ 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,
-          },
-        ],
+        options: [],
       }),
     ),
   ),