diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
index 3362622b7e..5fb47b1a9a 100644
--- a/apps/web/src/components/ChatView.tsx
+++ b/apps/web/src/components/ChatView.tsx
@@ -214,6 +214,7 @@ import {
   useComposerDraftStore,
   useComposerThreadDraft,
 } from "../composerDraftStore";
+import { shouldUseCompactComposerFooter } from "./composerFooterLayout";
 import { selectThreadTerminalState, useTerminalStateStore } from "../terminalStateStore";
 import { clamp } from "effect/Number";
 import { ComposerPromptEditor, type ComposerPromptEditorHandle } from "./ComposerPromptEditor";
@@ -639,6 +640,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
     useState<Record<string, number>>({});
   const [expandedWorkGroups, setExpandedWorkGroups] = useState<Record<string, boolean>>({});
   const [planSidebarOpen, setPlanSidebarOpen] = useState(false);
+  const [isComposerFooterCompact, setIsComposerFooterCompact] = useState(false);
   // Tracks whether the user explicitly dismissed the sidebar for the active turn.
   const planSidebarDismissedForTurnRef = useRef<string | null>(null);
   // When set, the thread-change reset effect will open the sidebar instead of closing it.
@@ -935,6 +937,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
     isComposerApprovalState ||
     pendingUserInputs.length > 0 ||
     (showPlanFollowUpPrompt && activeProposedPlan !== null);
+  const composerFooterHasWideActions = showPlanFollowUpPrompt || activePendingProgress !== null;
   useEffect(() => {
     if (!activePendingProgress) {
       return;
@@ -1672,6 +1675,24 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const toggleInteractionMode = useCallback(() => {
     handleInteractionModeChange(interactionMode === "plan" ? "default" : "plan");
   }, [handleInteractionModeChange, interactionMode]);
+  const toggleRuntimeMode = useCallback(() => {
+    void handleRuntimeModeChange(
+      runtimeMode === "full-access" ? "approval-required" : "full-access",
+    );
+  }, [handleRuntimeModeChange, runtimeMode]);
+  const togglePlanSidebar = useCallback(() => {
+    setPlanSidebarOpen((open) => {
+      if (open) {
+        const turnKey = activePlan?.turnId ?? activeProposedPlan?.turnId ?? null;
+        if (turnKey) {
+          planSidebarDismissedForTurnRef.current = turnKey;
+        }
+      } else {
+        planSidebarDismissedForTurnRef.current = null;
+      }
+      return !open;
+    });
+  }, [activePlan?.turnId, activeProposedPlan?.turnId]);
 
   const persistThreadSettingsForNextTurn = useCallback(
     async (input: {
@@ -1888,14 +1909,25 @@ export default function ChatView({ threadId }: ChatViewProps) {
   useLayoutEffect(() => {
     const composerForm = composerFormRef.current;
     if (!composerForm) return;
+    const measureComposerFormWidth = () => composerForm.clientWidth;
 
     composerFormHeightRef.current = composerForm.getBoundingClientRect().height;
+    setIsComposerFooterCompact(
+      shouldUseCompactComposerFooter(measureComposerFormWidth(), {
+        hasWideActions: composerFooterHasWideActions,
+      }),
+    );
     if (typeof ResizeObserver === "undefined") return;
 
     const observer = new ResizeObserver((entries) => {
       const [entry] = entries;
       if (!entry) return;
 
+      const nextCompact = shouldUseCompactComposerFooter(measureComposerFormWidth(), {
+        hasWideActions: composerFooterHasWideActions,
+      });
+      setIsComposerFooterCompact((previous) => (previous === nextCompact ? previous : nextCompact));
+
       const nextHeight = entry.contentRect.height;
       const previousHeight = composerFormHeightRef.current;
       composerFormHeightRef.current = nextHeight;
@@ -1909,7 +1941,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
     return () => {
       observer.disconnect();
     };
-  }, [activeThread?.id, scheduleStickToBottom]);
+  }, [activeThread?.id, composerFooterHasWideActions, scheduleStickToBottom]);
   useEffect(() => {
     if (!shouldAutoScrollRef.current) return;
     scheduleStickToBottom();
@@ -3468,7 +3500,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
         onDismiss={() => setThreadError(activeThread.id, null)}
       />
       {/* Main content area with optional plan sidebar */}
-      <div className="flex min-h-0 flex-1">
+      <div className="flex min-h-0 min-w-0 flex-1">
         {/* Chat column */}
         <div className="flex min-h-0 min-w-0 flex-1 flex-col">
 
@@ -3679,10 +3711,24 @@ export default function ChatView({ threadId }: ChatViewProps) {
                 />
               </div>
             ) : (
-              <div className="flex flex-wrap items-center justify-between gap-2 px-2.5 pb-2.5 sm:flex-nowrap sm:gap-0 sm:px-3 sm:pb-3">
-                <div className="flex min-w-0 flex-1 items-center gap-1 overflow-x-auto [scrollbar-width:none] [&::-webkit-scrollbar]:hidden sm:min-w-max sm:overflow-visible">
+              <div
+                data-chat-composer-footer="true"
+                className={cn(
+                  "flex items-center justify-between px-2.5 pb-2.5 sm:px-3 sm:pb-3",
+                  isComposerFooterCompact ? "gap-1.5" : "flex-wrap gap-2 sm:flex-nowrap sm:gap-0",
+                )}
+              >
+                <div
+                  className={cn(
+                    "flex min-w-0 flex-1 items-center",
+                    isComposerFooterCompact
+                      ? "gap-1 overflow-hidden"
+                      : "gap-1 overflow-x-auto [scrollbar-width:none] [&::-webkit-scrollbar]:hidden sm:min-w-max sm:overflow-visible",
+                  )}
+                >
                   {/* Provider/model picker */}
                   <ProviderModelPicker
+                    compact={isComposerFooterCompact}
                     provider={selectedProvider}
                     model={selectedModelForPickerWithCustomFallback}
                     lockedProvider={lockedProvider}
@@ -3690,107 +3736,108 @@ export default function ChatView({ threadId }: ChatViewProps) {
                     onProviderModelChange={onProviderModelSelect}
                   />
 
-                  {selectedProvider === "codex" && selectedEffort != null ? (
+                  {isComposerFooterCompact ? (
+                    <CompactComposerControlsMenu
+                      activePlan={Boolean(activePlan || activeProposedPlan || planSidebarOpen)}
+                      interactionMode={interactionMode}
+                      planSidebarOpen={planSidebarOpen}
+                      runtimeMode={runtimeMode}
+                      selectedEffort={selectedEffort}
+                      selectedProvider={selectedProvider}
+                      selectedCodexFastModeEnabled={selectedCodexFastModeEnabled}
+                      reasoningOptions={reasoningOptions}
+                      onEffortSelect={onEffortSelect}
+                      onCodexFastModeChange={onCodexFastModeChange}
+                      onToggleInteractionMode={toggleInteractionMode}
+                      onTogglePlanSidebar={togglePlanSidebar}
+                      onToggleRuntimeMode={toggleRuntimeMode}
+                    />
+                  ) : (
                     <>
+                      {selectedProvider === "codex" && selectedEffort != null ? (
+                        <>
+                          <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
+                          <CodexTraitsPicker
+                            effort={selectedEffort}
+                            fastModeEnabled={selectedCodexFastModeEnabled}
+                            options={reasoningOptions}
+                            onEffortChange={onEffortSelect}
+                            onFastModeChange={onCodexFastModeChange}
+                          />
+                        </>
+                      ) : null}
+
                       <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
-                      <CodexTraitsPicker
-                        effort={selectedEffort}
-                        fastModeEnabled={selectedCodexFastModeEnabled}
-                        options={reasoningOptions}
-                        onEffortChange={onEffortSelect}
-                        onFastModeChange={onCodexFastModeChange}
-                      />
-                    </>
-                  ) : null}
 
-                  {/* Divider */}
-                  <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
+                      <Button
+                        variant="ghost"
+                        className="shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80 sm:px-3"
+                        size="sm"
+                        type="button"
+                        onClick={toggleInteractionMode}
+                        title={
+                          interactionMode === "plan"
+                            ? "Plan mode — click to return to normal chat mode"
+                            : "Default mode — click to enter plan mode"
+                        }
+                      >
+                        <BotIcon />
+                        <span className="sr-only sm:not-sr-only">
+                          {interactionMode === "plan" ? "Plan" : "Chat"}
+                        </span>
+                      </Button>
 
-                  {/* Interaction mode toggle */}
-                  <Button
-                    variant="ghost"
-                    className="shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80 sm:px-3"
-                    size="sm"
-                    type="button"
-                    onClick={toggleInteractionMode}
-                    title={
-                      interactionMode === "plan"
-                        ? "Plan mode — click to return to normal chat mode"
-                        : "Default mode — click to enter plan mode"
-                    }
-                  >
-                    <BotIcon />
-                    <span className="sr-only sm:not-sr-only">
-                      {interactionMode === "plan" ? "Plan" : "Chat"}
-                    </span>
-                  </Button>
-
-                  {/* Divider */}
-                  <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
-
-                  {/* Runtime mode toggle */}
-                  <Button
-                    variant="ghost"
-                    className="shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80 sm:px-3"
-                    size="sm"
-                    type="button"
-                    onClick={() =>
-                      void handleRuntimeModeChange(
-                        runtimeMode === "full-access" ? "approval-required" : "full-access",
-                      )
-                    }
-                    title={
-                      runtimeMode === "full-access"
-                        ? "Full access — click to require approvals"
-                        : "Approval required — click for full access"
-                    }
-                  >
-                    {runtimeMode === "full-access" ? <LockOpenIcon /> : <LockIcon />}
-                    <span className="sr-only sm:not-sr-only">
-                      {runtimeMode === "full-access" ? "Full access" : "Supervised"}
-                    </span>
-                  </Button>
-
-                  {/* Plan sidebar toggle */}
-                  {(activePlan || activeProposedPlan || planSidebarOpen) ? (
-                    <>
                       <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
+
                       <Button
                         variant="ghost"
-                        className={cn(
-                          "shrink-0 whitespace-nowrap px-2 sm:px-3",
-                          planSidebarOpen
-                            ? "text-blue-400 hover:text-blue-300"
-                            : "text-muted-foreground/70 hover:text-foreground/80",
-                        )}
+                        className="shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80 sm:px-3"
                         size="sm"
                         type="button"
-                        onClick={() => {
-                          setPlanSidebarOpen((open) => {
-                            if (open) {
-                              // Closing: track dismissal for current turn
-                              const turnKey = activePlan?.turnId ?? activeProposedPlan?.turnId ?? null;
-                              if (turnKey) {
-                                planSidebarDismissedForTurnRef.current = turnKey;
-                              }
-                            } else {
-                              // Re-opening: clear dismissal tracking
-                              planSidebarDismissedForTurnRef.current = null;
-                            }
-                            return !open;
-                          });
-                        }}
-                        title={planSidebarOpen ? "Hide plan sidebar" : "Show plan sidebar"}
+                        onClick={() =>
+                          void handleRuntimeModeChange(
+                            runtimeMode === "full-access" ? "approval-required" : "full-access",
+                          )
+                        }
+                        title={
+                          runtimeMode === "full-access"
+                            ? "Full access — click to require approvals"
+                            : "Approval required — click for full access"
+                        }
                       >
-                        <ListTodoIcon />
-                        <span className="sr-only sm:not-sr-only">Plan</span>
+                        {runtimeMode === "full-access" ? <LockOpenIcon /> : <LockIcon />}
+                        <span className="sr-only sm:not-sr-only">
+                          {runtimeMode === "full-access" ? "Full access" : "Supervised"}
+                        </span>
                       </Button>
+
+                      {(activePlan || activeProposedPlan || planSidebarOpen) ? (
+                        <>
+                          <Separator orientation="vertical" className="mx-0.5 hidden h-4 sm:block" />
+                          <Button
+                            variant="ghost"
+                            className={cn(
+                              "shrink-0 whitespace-nowrap px-2 sm:px-3",
+                              planSidebarOpen
+                                ? "text-blue-400 hover:text-blue-300"
+                                : "text-muted-foreground/70 hover:text-foreground/80",
+                            )}
+                            size="sm"
+                            type="button"
+                            onClick={togglePlanSidebar}
+                            title={planSidebarOpen ? "Hide plan sidebar" : "Show plan sidebar"}
+                          >
+                            <ListTodoIcon />
+                            <span className="sr-only sm:not-sr-only">Plan</span>
+                          </Button>
+                        </>
+                      ) : null}
                     </>
-                  ) : null}
+                  )}
                 </div>
 
                 {/* Right side: send / stop button */}
-                <div className="flex shrink-0 items-center gap-2">
+                <div data-chat-composer-actions="right" className="flex shrink-0 items-center gap-2">
                   {isPreparingWorktree ? (
                     <span className="text-muted-foreground/70 text-xs">Preparing worktree...</span>
                   ) : null}
@@ -3953,6 +4000,15 @@ export default function ChatView({ threadId }: ChatViewProps) {
         </form>
       </div>
 
+      {isGitRepo && (
+        <BranchToolbar
+          threadId={activeThread.id}
+          onEnvModeChange={onEnvModeChange}
+          envLocked={envLocked}
+          onComposerFocusRequest={scheduleComposerFocus}
+        />
+      )}
+
         </div>{/* end chat column */}
 
         {/* Plan sidebar */}
@@ -3974,15 +4030,6 @@ export default function ChatView({ threadId }: ChatViewProps) {
         ) : null}
       </div>{/* end horizontal flex container */}
 
-      {isGitRepo && (
-        <BranchToolbar
-          threadId={activeThread.id}
-          onEnvModeChange={onEnvModeChange}
-          envLocked={envLocked}
-          onComposerFocusRequest={scheduleComposerFocus}
-        />
-      )}
-
       {(() => {
         if (!terminalState.terminalOpen || !activeProject) {
           return null;
@@ -5534,6 +5581,7 @@ const ProviderModelPicker = memo(function ProviderModelPicker(props: {
   model: ModelSlug;
   lockedProvider: ProviderKind | null;
   modelOptionsByProvider: Record<ProviderKind, ReadonlyArray<{ slug: string; name: string }>>;
+  compact?: boolean;
   disabled?: boolean;
   onProviderModelChange: (provider: ProviderKind, model: ModelSlug) => void;
 }) {
@@ -5559,12 +5607,20 @@ const ProviderModelPicker = memo(function ProviderModelPicker(props: {
           <Button
             size="sm"
             variant="ghost"
-            className="shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80 sm:px-3"
+            className={cn(
+              "min-w-0 shrink-0 whitespace-nowrap px-2 text-muted-foreground/70 hover:text-foreground/80",
+              props.compact ? "max-w-[10.5rem]" : "sm:px-3",
+            )}
             disabled={props.disabled}
           />
         }
       >
-        <span className="flex min-w-0 items-center gap-2">
+        <span
+          className={cn(
+            "flex min-w-0 items-center gap-2",
+            props.compact ? "max-w-[9rem]" : undefined,
+          )}
+        >
           <ProviderIcon aria-hidden="true" className="size-4 shrink-0 text-muted-foreground/70" />
           <span className="truncate">{selectedModelLabel}</span>
           <ChevronDownIcon aria-hidden="true" className="size-3 opacity-60" />
@@ -5654,6 +5710,122 @@ const ProviderModelPicker = memo(function ProviderModelPicker(props: {
   );
 });
 
+const CompactComposerControlsMenu = memo(function CompactComposerControlsMenu(props: {
+  activePlan: boolean;
+  interactionMode: ProviderInteractionMode;
+  planSidebarOpen: boolean;
+  runtimeMode: RuntimeMode;
+  selectedEffort: CodexReasoningEffort | null;
+  selectedProvider: ProviderKind;
+  selectedCodexFastModeEnabled: boolean;
+  reasoningOptions: ReadonlyArray<CodexReasoningEffort>;
+  onEffortSelect: (effort: CodexReasoningEffort) => void;
+  onCodexFastModeChange: (enabled: boolean) => void;
+  onToggleInteractionMode: () => void;
+  onTogglePlanSidebar: () => void;
+  onToggleRuntimeMode: () => void;
+}) {
+  const defaultReasoningEffort = getDefaultReasoningEffort("codex");
+  const reasoningLabelByOption: Record<CodexReasoningEffort, string> = {
+    low: "Low",
+    medium: "Medium",
+    high: "High",
+    xhigh: "Extra High",
+  };
+
+  return (
+    <Menu>
+      <MenuTrigger
+        render={
+          <Button
+            size="sm"
+            variant="ghost"
+            className="shrink-0 px-2 text-muted-foreground/70 hover:text-foreground/80"
+            aria-label="More composer controls"
+          />
+        }
+      >
+        <EllipsisIcon aria-hidden="true" className="size-4" />
+      </MenuTrigger>
+      <MenuPopup align="start">
+        {props.selectedProvider === "codex" && props.selectedEffort != null ? (
+          <>
+            <MenuGroup>
+              <div className="px-2 py-1.5 font-medium text-muted-foreground text-xs">Reasoning</div>
+              <MenuRadioGroup
+                value={props.selectedEffort}
+                onValueChange={(value) => {
+                  if (!value) return;
+                  const nextEffort = props.reasoningOptions.find((option) => option === value);
+                  if (!nextEffort) return;
+                  props.onEffortSelect(nextEffort);
+                }}
+              >
+                {props.reasoningOptions.map((effort) => (
+                  <MenuRadioItem key={effort} value={effort}>
+                    {reasoningLabelByOption[effort]}
+                    {effort === defaultReasoningEffort ? " (default)" : ""}
+                  </MenuRadioItem>
+                ))}
+              </MenuRadioGroup>
+            </MenuGroup>
+            <MenuDivider />
+            <MenuGroup>
+              <div className="px-2 py-1.5 font-medium text-muted-foreground text-xs">Fast Mode</div>
+              <MenuRadioGroup
+                value={props.selectedCodexFastModeEnabled ? "on" : "off"}
+                onValueChange={(value) => {
+                  props.onCodexFastModeChange(value === "on");
+                }}
+              >
+                <MenuRadioItem value="off">off</MenuRadioItem>
+                <MenuRadioItem value="on">on</MenuRadioItem>
+              </MenuRadioGroup>
+            </MenuGroup>
+            <MenuDivider />
+          </>
+        ) : null}
+        <MenuGroup>
+          <div className="px-2 py-1.5 font-medium text-muted-foreground text-xs">Mode</div>
+          <MenuRadioGroup
+            value={props.interactionMode}
+            onValueChange={(value) => {
+              if (!value || value === props.interactionMode) return;
+              props.onToggleInteractionMode();
+            }}
+          >
+            <MenuRadioItem value="default">Chat</MenuRadioItem>
+            <MenuRadioItem value="plan">Plan</MenuRadioItem>
+          </MenuRadioGroup>
+        </MenuGroup>
+        <MenuDivider />
+        <MenuGroup>
+          <div className="px-2 py-1.5 font-medium text-muted-foreground text-xs">Access</div>
+          <MenuRadioGroup
+            value={props.runtimeMode}
+            onValueChange={(value) => {
+              if (!value || value === props.runtimeMode) return;
+              props.onToggleRuntimeMode();
+            }}
+          >
+            <MenuRadioItem value="approval-required">Supervised</MenuRadioItem>
+            <MenuRadioItem value="full-access">Full access</MenuRadioItem>
+          </MenuRadioGroup>
+        </MenuGroup>
+        {props.activePlan ? (
+          <>
+            <MenuDivider />
+            <MenuItem onClick={props.onTogglePlanSidebar}>
+              <ListTodoIcon className="size-4 shrink-0" />
+              {props.planSidebarOpen ? "Hide plan sidebar" : "Show plan sidebar"}
+            </MenuItem>
+          </>
+        ) : null}
+      </MenuPopup>
+    </Menu>
+  );
+});
+
 const CodexTraitsPicker = memo(function CodexTraitsPicker(props: {
   effort: CodexReasoningEffort;
   fastModeEnabled: boolean;
diff --git a/apps/web/src/components/composerFooterLayout.test.ts b/apps/web/src/components/composerFooterLayout.test.ts
new file mode 100644
index 0000000000..d5325f5bda
--- /dev/null
+++ b/apps/web/src/components/composerFooterLayout.test.ts
@@ -0,0 +1,37 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX,
+  COMPOSER_FOOTER_WIDE_ACTIONS_COMPACT_BREAKPOINT_PX,
+  shouldUseCompactComposerFooter,
+} from "./composerFooterLayout";
+
+describe("shouldUseCompactComposerFooter", () => {
+  it("stays expanded without a measured width", () => {
+    expect(shouldUseCompactComposerFooter(null)).toBe(false);
+  });
+
+  it("switches to compact mode below the breakpoint", () => {
+    expect(shouldUseCompactComposerFooter(COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX - 1)).toBe(true);
+  });
+
+  it("stays expanded at and above the breakpoint", () => {
+    expect(shouldUseCompactComposerFooter(COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX)).toBe(false);
+    expect(shouldUseCompactComposerFooter(COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX + 48)).toBe(
+      false,
+    );
+  });
+
+  it("uses a higher breakpoint for wide action states", () => {
+    expect(
+      shouldUseCompactComposerFooter(COMPOSER_FOOTER_WIDE_ACTIONS_COMPACT_BREAKPOINT_PX - 1, {
+        hasWideActions: true,
+      }),
+    ).toBe(true);
+    expect(
+      shouldUseCompactComposerFooter(COMPOSER_FOOTER_WIDE_ACTIONS_COMPACT_BREAKPOINT_PX, {
+        hasWideActions: true,
+      }),
+    ).toBe(false);
+  });
+});
diff --git a/apps/web/src/components/composerFooterLayout.ts b/apps/web/src/components/composerFooterLayout.ts
new file mode 100644
index 0000000000..3cf994fc14
--- /dev/null
+++ b/apps/web/src/components/composerFooterLayout.ts
@@ -0,0 +1,12 @@
+export const COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX = 620;
+export const COMPOSER_FOOTER_WIDE_ACTIONS_COMPACT_BREAKPOINT_PX = 720;
+
+export function shouldUseCompactComposerFooter(
+  width: number | null,
+  options?: { hasWideActions?: boolean },
+): boolean {
+  const breakpoint = options?.hasWideActions
+    ? COMPOSER_FOOTER_WIDE_ACTIONS_COMPACT_BREAKPOINT_PX
+    : COMPOSER_FOOTER_COMPACT_BREAKPOINT_PX;
+  return width !== null && width < breakpoint;
+}
diff --git a/apps/web/src/components/ui/sidebar.tsx b/apps/web/src/components/ui/sidebar.tsx
index ba77bddc27..16b9ec4ed3 100644
--- a/apps/web/src/components/ui/sidebar.tsx
+++ b/apps/web/src/components/ui/sidebar.tsx
@@ -595,7 +595,7 @@ function SidebarInset({ className, ...props }: React.ComponentProps<"main">) {
   return (
     <main
       className={cn(
-        "relative flex w-full flex-1 flex-col bg-background",
+        "relative flex min-w-0 w-full flex-1 flex-col bg-background",
         "md:peer-data-[variant=inset]:peer-data-[state=collapsed]:ms-2 md:peer-data-[variant=inset]:m-2 md:peer-data-[variant=inset]:ms-0 md:peer-data-[variant=inset]:rounded-xl md:peer-data-[variant=inset]:shadow-sm/5",
         className,
       )}
diff --git a/apps/web/src/routes/_chat.$threadId.tsx b/apps/web/src/routes/_chat.$threadId.tsx
index 2593eb7605..ccd2002777 100644
--- a/apps/web/src/routes/_chat.$threadId.tsx
+++ b/apps/web/src/routes/_chat.$threadId.tsx
@@ -15,6 +15,7 @@ const DIFF_INLINE_LAYOUT_MEDIA_QUERY = "(max-width: 1180px)";
 const DIFF_INLINE_SIDEBAR_WIDTH_STORAGE_KEY = "chat_diff_sidebar_width";
 const DIFF_INLINE_DEFAULT_WIDTH = "clamp(28rem,48vw,44rem)";
 const DIFF_INLINE_SIDEBAR_MIN_WIDTH = 26 * 16;
+const COMPOSER_COMPACT_MIN_LEFT_CONTROLS_WIDTH_PX = 208;
 
 const DiffPanelSheet = (props: {
   children: ReactNode;
@@ -91,8 +92,23 @@ const DiffPanelInlineSidebar = (props: {
         composerViewport.clientWidth - viewportPaddingLeft - viewportPaddingRight,
       );
       const formRect = composerForm.getBoundingClientRect();
+      const composerFooter = composerForm.querySelector<HTMLElement>("[data-chat-composer-footer='true']");
+      const composerRightActions = composerForm.querySelector<HTMLElement>(
+        "[data-chat-composer-actions='right']",
+      );
+      const composerRightActionsWidth = composerRightActions?.getBoundingClientRect().width ?? 0;
+      const composerFooterGap = composerFooter
+        ? Number.parseFloat(window.getComputedStyle(composerFooter).columnGap) ||
+          Number.parseFloat(window.getComputedStyle(composerFooter).gap) ||
+          0
+        : 0;
+      const minimumComposerWidth =
+        COMPOSER_COMPACT_MIN_LEFT_CONTROLS_WIDTH_PX +
+        composerRightActionsWidth +
+        composerFooterGap;
       const hasComposerOverflow = composerForm.scrollWidth > composerForm.clientWidth + 0.5;
       const overflowsViewport = formRect.width > viewportContentWidth + 0.5;
+      const violatesMinimumComposerWidth = composerForm.clientWidth + 0.5 < minimumComposerWidth;
 
       if (previousSidebarWidth.length > 0) {
         wrapper.style.setProperty("--sidebar-width", previousSidebarWidth);
@@ -100,7 +116,7 @@ const DiffPanelInlineSidebar = (props: {
         wrapper.style.removeProperty("--sidebar-width");
       }
 
-      return !hasComposerOverflow && !overflowsViewport;
+      return !hasComposerOverflow && !overflowsViewport && !violatesMinimumComposerWidth;
     },
     [],
   );