feat(web): add a sticky steer bar at the bottom of run views

Adds a single-row text input + Send button that pins to the viewport
bottom on every run-detail tab as a placeholder for the future
steering composer (will replace the modal). Renders mutually
exclusive with InterviewDock: the dock takes precedence on blocked
runs with pending questions, otherwise the steer bar shows. Reuses
the existing --fabro-interview-dock-clearance variable so consumers
that already pad for the dock pick up the steer bar's clearance too.
Send is intentionally a no-op for now until the steering API is
swapped over from the modal.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/fabro-web/app/components/steer-bar.tsx

@@ -0,0 +1,58 @@
+import { useState, type FormEvent, type KeyboardEvent } from "react";
+
+export interface SteerBarProps {
+  runId: string;
+}
+
+export function SteerBar({ runId: _runId }: SteerBarProps) {
+  const [text, setText] = useState("");
+  const trimmed = text.trim();
+  const canSubmit = trimmed.length > 0;
+
+  function handleSubmit(e: FormEvent) {
+    e.preventDefault();
+    if (!canSubmit) return;
+    setText("");
+  }
+
+  function handleKeyDown(e: KeyboardEvent<HTMLTextAreaElement>) {
+    if (e.key === "Enter" && !e.shiftKey) {
+      e.preventDefault();
+      if (canSubmit) {
+        setText("");
+      }
+    }
+  }
+
+  return (
+    <div className="pointer-events-none fixed inset-x-0 bottom-0 z-30">
+      <div className="bg-linear-to-t from-page via-page/80 to-transparent pt-10">
+        <div className="pointer-events-auto mx-auto max-w-5xl px-4 pb-4 sm:px-6 lg:px-8">
+          <form
+            onSubmit={handleSubmit}
+            aria-label="Steer running agent"
+            className="flex items-end gap-2 rounded-2xl bg-panel p-2 shadow-[0_-12px_40px_-8px_rgba(0,0,0,0.5)] ring-1 ring-line-strong"
+          >
+            <textarea
+              value={text}
+              onChange={(e) => setText(e.target.value)}
+              onKeyDown={handleKeyDown}
+              placeholder="Steer the agent…"
+              rows={1}
+              maxLength={8192}
+              aria-label="Steering message"
+              className="flex-1 resize-none bg-transparent px-3 py-2 text-sm text-fg outline-hidden placeholder:text-fg-muted"
+            />
+            <button
+              type="submit"
+              disabled={!canSubmit}
+              className="inline-flex shrink-0 items-center justify-center rounded-lg bg-teal-500 px-4 py-2 text-sm font-medium text-on-primary transition-colors hover:bg-teal-300 focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-teal-500 disabled:cursor-not-allowed disabled:opacity-60 disabled:hover:bg-teal-500"
+            >
+              Send
+            </button>
+          </form>
+        </div>
+      </div>
+    </div>
+  );
+}

apps/fabro-web/app/routes/run-detail.tsx

@@ -17,6 +17,7 @@ import { Link, Outlet, useLocation, useMatches } from "react-router";
 import { Menu, MenuButton, MenuItem, MenuItems } from "@headlessui/react";
 
 import { InterviewDock } from "../components/interview-dock";
+import { SteerBar } from "../components/steer-bar";
 import { SteerComposer } from "../components/steer-composer";
 import { ErrorState } from "../components/state";
 import { useToast } from "../components/toast";
@@ -212,8 +213,9 @@ export default function RunDetail({ params }: { params: { id: string } }) {
   const archivePending = archiveMutation.isMutating;
   const unarchivePending = unarchiveMutation.isMutating;
   const hasPendingQuestions = isBlocked && pendingQuestions.length > 0;
-  const rootStyle = fullHeight && hasPendingQuestions
-    ? ({ "--fabro-interview-dock-clearance": "18rem" } as CSSProperties)
+  const dockClearance = hasPendingQuestions ? "18rem" : "5rem";
+  const rootStyle = fullHeight
+    ? ({ "--fabro-interview-dock-clearance": dockClearance } as CSSProperties)
     : undefined;
 
   return (
@@ -346,6 +348,8 @@ export default function RunDetail({ params }: { params: { id: string } }) {
         onClose={() => setSteerOpen(false)}
       />
 
+      {!hasPendingQuestions && <SteerBar runId={params.id} />}
+
       {hasPendingQuestions && (
         fullHeight ? (
           <InterviewDock runId={params.id} questions={pendingQuestions} />