diff --git a/src/cli/config-manager/bun-install.ts b/src/cli/config-manager/bun-install.ts
index f24e77fa26..e763941a6a 100644
--- a/src/cli/config-manager/bun-install.ts
+++ b/src/cli/config-manager/bun-install.ts
@@ -1,4 +1,4 @@
-import { getConfigDir } from "./config-context"
+import { getOpenCodeConfigDir } from "../../shared"
 
 const BUN_INSTALL_TIMEOUT_SECONDS = 60
 const BUN_INSTALL_TIMEOUT_MS = BUN_INSTALL_TIMEOUT_SECONDS * 1000
@@ -17,7 +17,7 @@ export async function runBunInstall(): Promise<boolean> {
 export async function runBunInstallWithDetails(): Promise<BunInstallResult> {
   try {
     const proc = Bun.spawn(["bun", "install"], {
-      cwd: getConfigDir(),
+      cwd: getOpenCodeConfigDir({ binary: "opencode" }),
       stdout: "inherit",
       stderr: "inherit",
     })
@@ -39,7 +39,7 @@ export async function runBunInstallWithDetails(): Promise<BunInstallResult> {
       return {
         success: false,
         timedOut: true,
-        error: `bun install timed out after ${BUN_INSTALL_TIMEOUT_SECONDS} seconds. Try running manually: cd ${getConfigDir()} && bun i`,
+        error: `bun install timed out after ${BUN_INSTALL_TIMEOUT_SECONDS} seconds. Try running manually: cd ${getOpenCodeConfigDir({ binary: "opencode" })} && bun i`,
       }
     }
 
diff --git a/src/cli/model-fallback-requirements.ts b/src/cli/model-fallback-requirements.ts
index f3f43e60ba..1f1e9d78ca 100644
--- a/src/cli/model-fallback-requirements.ts
+++ b/src/cli/model-fallback-requirements.ts
@@ -23,7 +23,7 @@ export const CLI_AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   },
   oracle: {
     fallbackChain: [
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
     ],
@@ -45,7 +45,7 @@ export const CLI_AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   "multimodal-looker": {
     fallbackChain: [
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-flash" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
       { providers: ["zai-coding-plan"], model: "glm-4.6v" },
       { providers: ["kimi-for-coding"], model: "k2p5" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
@@ -58,7 +58,7 @@ export const CLI_AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
       { providers: ["kimi-for-coding"], model: "k2p5" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
   },
@@ -67,13 +67,13 @@ export const CLI_AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
       { providers: ["kimi-for-coding"], model: "k2p5" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
     ],
   },
   momus: {
     fallbackChain: [
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "medium" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "medium" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
     ],
@@ -83,7 +83,7 @@ export const CLI_AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
       { providers: ["kimi-for-coding"], model: "k2p5" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-sonnet-4-5" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
   },
@@ -117,7 +117,7 @@ export const CLI_CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> =
     fallbackChain: [
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
     ],
     requiresModel: "gemini-3-pro",
   },
@@ -138,7 +138,7 @@ export const CLI_CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> =
   "unspecified-high": {
     fallbackChain: [
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
   },
diff --git a/src/shared/migration.test.ts b/src/shared/migration.test.ts
index 7846cc7258..ecc8655afb 100644
--- a/src/shared/migration.test.ts
+++ b/src/shared/migration.test.ts
@@ -525,7 +525,13 @@ describe("MODEL_VERSION_MAP", () => {
     // then: Should contain correct mapping
     expect(MODEL_VERSION_MAP["anthropic/claude-opus-4-5"]).toBe("anthropic/claude-opus-4-6")
   })
-})
+
+  test("maps openai/gpt-5.3 to openai/gpt-5.3-codex", () => {
+    // given/when: Check MODEL_VERSION_MAP
+    // then: bare gpt-5.3 should migrate to gpt-5.3-codex
+    expect(MODEL_VERSION_MAP["openai/gpt-5.3"]).toBe("openai/gpt-5.3-codex")
+  })
+}
 
 describe("migrateModelVersions", () => {
   test("#given a config with gpt-5.2-codex model #when migrating model versions #then does not overwrite with non-existent gpt-5.3-codex", () => {
@@ -559,6 +565,22 @@ describe("migrateModelVersions", () => {
     expect(prometheus.model).toBe("anthropic/claude-opus-4-6")
   })
 
+
+  test("replaces bare openai/gpt-5.3 with openai/gpt-5.3-codex", () => {
+    // given: Agent config with bare gpt-5.3 (non-codex)
+    const agents = {
+      momus: { model: "openai/gpt-5.3", variant: "medium" },
+    }
+
+    // when: Migrate model versions
+    const { migrated, changed } = migrateModelVersions(agents)
+
+    // then: Model should be updated to codex variant
+    expect(changed).toBe(true)
+    const momus = migrated["momus"] as Record<string, unknown>
+    expect(momus.model).toBe("openai/gpt-5.3-codex")
+    expect(momus.variant).toBe("medium")
+  })
   test("leaves unknown model strings untouched", () => {
     // given: Agent config with unknown model
     const agents = {
diff --git a/src/shared/migration/model-versions.ts b/src/shared/migration/model-versions.ts
index b3df8cdd2e..a32f576dbe 100644
--- a/src/shared/migration/model-versions.ts
+++ b/src/shared/migration/model-versions.ts
@@ -8,6 +8,7 @@
 export const MODEL_VERSION_MAP: Record<string, string> = {
   "anthropic/claude-opus-4-5": "anthropic/claude-opus-4-6",
   "anthropic/claude-sonnet-4-5": "anthropic/claude-sonnet-4-6",
+  "openai/gpt-5.3": "openai/gpt-5.3-codex",
 }
 
 function migrationKey(oldModel: string, newModel: string): string {
diff --git a/src/shared/model-requirements.test.ts b/src/shared/model-requirements.test.ts
index 2991775eb8..9b30609cf6 100644
--- a/src/shared/model-requirements.test.ts
+++ b/src/shared/model-requirements.test.ts
@@ -7,19 +7,19 @@ import {
 } from "./model-requirements"
 
 describe("AGENT_MODEL_REQUIREMENTS", () => {
-  test("oracle has valid fallbackChain with gpt-5.2 as primary", () => {
+  test("oracle has valid fallbackChain with gpt-5.3-codex as primary", () => {
     // given - oracle agent requirement
     const oracle = AGENT_MODEL_REQUIREMENTS["oracle"]
 
     // when - accessing oracle requirement
-    // then - fallbackChain exists with gpt-5.2 as first entry
+    // then - fallbackChain exists with gpt-5.3-codex as first entry
     expect(oracle).toBeDefined()
     expect(oracle.fallbackChain).toBeArray()
     expect(oracle.fallbackChain.length).toBeGreaterThan(0)
 
     const primary = oracle.fallbackChain[0]
     expect(primary.providers).toContain("openai")
-    expect(primary.model).toBe("gpt-5.2")
+    expect(primary.model).toBe("gpt-5.3-codex")
     expect(primary.variant).toBe("high")
   })
 
@@ -137,18 +137,18 @@ describe("AGENT_MODEL_REQUIREMENTS", () => {
     expect(primary.variant).toBe("max")
   })
 
-  test("momus has valid fallbackChain with gpt-5.2 as primary", () => {
+  test("momus has valid fallbackChain with gpt-5.3-codex as primary", () => {
     // given - momus agent requirement
     const momus = AGENT_MODEL_REQUIREMENTS["momus"]
 
     // when - accessing Momus requirement
-    // then - fallbackChain exists with gpt-5.2 as first entry, variant medium
+    // then - fallbackChain exists with gpt-5.3-codex as first entry, variant medium
     expect(momus).toBeDefined()
     expect(momus.fallbackChain).toBeArray()
     expect(momus.fallbackChain.length).toBeGreaterThan(0)
 
     const primary = momus.fallbackChain[0]
-    expect(primary.model).toBe("gpt-5.2")
+    expect(primary.model).toBe("gpt-5.3-codex")
     expect(primary.variant).toBe("medium")
     expect(primary.providers[0]).toBe("openai")
   })
diff --git a/src/shared/model-requirements.ts b/src/shared/model-requirements.ts
index 9a795ba76a..5a8cf24efa 100644
--- a/src/shared/model-requirements.ts
+++ b/src/shared/model-requirements.ts
@@ -30,7 +30,7 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   },
   oracle: {
     fallbackChain: [
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
     ],
@@ -54,7 +54,7 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     fallbackChain: [
       { providers: ["opencode"], model: "kimi-k2.5-free" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-flash" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
       { providers: ["zai-coding-plan"], model: "glm-4.6v" },
       { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5-nano" },
     ],
@@ -62,7 +62,7 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   prometheus: {
     fallbackChain: [
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
@@ -71,13 +71,13 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     fallbackChain: [
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
       { providers: ["opencode"], model: "kimi-k2.5-free" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
     ],
   },
   momus: {
     fallbackChain: [
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "medium" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "medium" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
     ],
@@ -86,7 +86,7 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     fallbackChain: [
       { providers: ["opencode"], model: "kimi-k2.5-free" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-sonnet-4-6" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
     ],
   },
 }
@@ -118,7 +118,7 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     fallbackChain: [
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex" },
     ],
     requiresModel: "gemini-3-pro",
   },
@@ -139,7 +139,7 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   "unspecified-high": {
     fallbackChain: [
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-6", variant: "max" },
-      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.3-codex", variant: "high" },
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
   },