diff --git a/client/src/lib/api.ts b/client/src/lib/api.ts
index b101170c..1b27bbd4 100644
--- a/client/src/lib/api.ts
+++ b/client/src/lib/api.ts
@@ -388,6 +388,7 @@ import type {
   LaneCounts,
   LaneGitFacts,
   LaneRuntime,
+  LaneTool,
   ModelPricing,
   NamedLock,
   PipelineStats,
@@ -1569,8 +1570,9 @@ export const api = {
       if (options?.laneId !== undefined) qs.set("laneId", String(options.laneId));
       return request<{ items: DashboardRunHistoryItem[] }>(`/run/history?${qs.toString()}`);
     },
-    /** GET /api/run/binary - whether `claude` was found on PATH. */
-    binary: () => request<{ found: boolean; path: string | null }>("/run/binary"),
+    /** GET /api/run/binary - whether the lane's CLI (`claude` or `codex`) was found on PATH. */
+    binary: (tool: LaneTool = "claude") =>
+      request<{ found: boolean; path: string | null }>(`/run/binary?tool=${tool}`),
     /** GET /api/run/tmux - whether the `tmux` binary was found on PATH. */
     tmuxAvailable: () => request<{ available: boolean }>("/run/tmux"),
     /** GET /api/run/cwds - suggested working directories for the cwd picker. */
@@ -1907,7 +1909,7 @@ export const api = {
      *   location isn't tied to a specific project (e.g. Sagi's mascot lane).
      * @returns `{ lane, created }` — the lane (newly created or existing) and whether it was created.
      */
-    ensure: (body: { cwd?: string; title?: string; pipeline?: string }) =>
+    ensure: (body: { cwd?: string; title?: string; pipeline?: string; tool?: LaneTool }) =>
       request<{ lane: Lane; created: boolean }>("/lanes/ensure", {
         method: "POST",
         body: JSON.stringify(body),
@@ -1955,6 +1957,7 @@ export const api = {
       base?: string;
       branch?: string;
       pipeline?: string;
+      tool?: LaneTool;
     }) =>
       request<{ lane: Lane }>("/lanes/worktree", {
         method: "POST",
@@ -2589,6 +2592,9 @@ export type EffortLevel = "" | "low" | "medium" | "high" | "xhigh" | "max";
  *  state on every read, never cached. */
 export type RunStatus = "running" | "gone";
 
+export type CodexSandbox = "read-only" | "workspace-write" | "danger-full-access";
+export type CodexApproval = "on-request" | "never";
+
 /** Body for POST /api/run - parameters for starting a lane's terminal run. */
 export interface RunStartArgs {
   laneId: number;
@@ -2601,6 +2607,12 @@ export interface RunStartArgs {
   /** Sent as `claude`'s first positional message once the pane boots; omit
    *  to just open the pane and let the user type. */
   initialPrompt?: string;
+  /** Codex only: `-s`. Ignored by a claude lane. */
+  sandbox?: CodexSandbox;
+  /** Codex only: `-a`. Ignored by a claude lane. */
+  approval?: CodexApproval;
+  /** Codex only: `codex resume --last` instead of picking a session id. */
+  resumeLast?: boolean;
 }
 
 /** A lane's tmux-backed terminal run — one per lane, id is the tmux session
@@ -2620,6 +2632,7 @@ export interface RunHandle {
   startedAt: string | null;
   /** Initial prompt preview (first 500 chars), null when not provided. */
   promptPreview: string | null;
+  tool: LaneTool;
 }
 
 /** Response shape of GET /api/run. */
@@ -2650,6 +2663,7 @@ export interface DashboardRunHistoryItem {
   started_at: string;
   ended_at: string | null;
   isLive: boolean;
+  tool: LaneTool;
 }
 
 /** One suggested working directory for the Run page's cwd picker. */
diff --git a/client/src/lib/types.ts b/client/src/lib/types.ts
index 5d5d7b90..c3d86f45 100644
--- a/client/src/lib/types.ts
+++ b/client/src/lib/types.ts
@@ -2281,12 +2281,17 @@ export interface ProofFeature {
   mtime: number;
 }
 
+/** Which CLI drives a lane's pane. Fixed at lane creation and never patched. */
+export type LaneTool = "claude" | "codex";
+
 export interface Lane {
   id: number;
   title: string;
   cwd: string;
   branch: string | null;
   kind: "managed" | "adopted";
+  /** The CLI this lane's runs spawn. Immutable once the lane exists. */
+  tool: LaneTool;
   /** For a managed worktree lane, the repo it was provisioned from. Null for
    *  an adopted lane (it IS a source repo, not a worktree of one). */
   source_repo: string | null;