diff --git a/web/app/workflows/[id]/page.tsx b/web/app/workflows/[id]/page.tsx
index bd6e2b7..dc0992e 100644
--- a/web/app/workflows/[id]/page.tsx
+++ b/web/app/workflows/[id]/page.tsx
@@ -35,6 +35,14 @@ function DefaultBadge() {
     );
 }
 
+function AdhocBadge() {
+    return (
+        <span className="rounded px-1.5 py-0.5 font-mono text-[10px] uppercase bg-signal/15 text-signal">
+            ad-hoc
+        </span>
+    );
+}
+
 export default function WorkflowBuilder() {
     const params = useParams<{ id: string }>();
     const id = params.id;
@@ -49,8 +57,10 @@ export default function WorkflowBuilder() {
     const [error, setError] = useState<string | null>(null);
     const [notice, setNotice] = useState<string | null>(null);
     const [importing, setImporting] = useState(false);
+    const [importingInline, setImportingInline] = useState(false);
     const [syncing, setSyncing] = useState(false);
     const fileInputRef = useRef<HTMLInputElement>(null);
+    const inlineFileInputRef = useRef<HTMLInputElement>(null);
     const [groupKeys, setGroupKeys] = useState<Record<string, string[]>>({});
     const [editWorkflowOpen, setEditWorkflowOpen] = useState(false);
     const [editingStep, setEditingStep] = useState<WorkflowStep | null>(null);
@@ -140,6 +150,45 @@ export default function WorkflowBuilder() {
         setWf({ ...wf, steps: resequence(next) });
     };
 
+    const appendRef = (ref: WorkflowStepRef) => {
+        setWf({ ...wf, steps: resequence([...sortedSteps, ref]) });
+    };
+
+    const addAdhocStep = () => {
+        appendRef({
+            inline: {
+                step_id: "",
+                name: "New ad-hoc step",
+                description: "",
+                interpreter: "bash",
+                script: "",
+                declared_outputs: [],
+                declared_inputs: [],
+                secret_refs: [],
+            },
+            order: wf.steps.length,
+            on_failure: "stop",
+            max_retries: 0,
+        });
+    };
+
+    const onImportInline = async (e: React.ChangeEvent<HTMLInputElement>) => {
+        const file = e.target.files?.[0];
+        if (!file) return;
+        setImportingInline(true);
+        setError(null);
+        try {
+            const doc = JSON.parse(await file.text());
+            const step = await api.parseStep(doc);
+            appendRef({ inline: step, order: wf.steps.length, on_failure: "stop", max_retries: 0 });
+        } catch (err) {
+            setError((err as Error).message);
+        } finally {
+            setImportingInline(false);
+            e.target.value = "";
+        }
+    };
+
     const moveStep = (from: number, pos: number) => {
         const next = [...sortedSteps];
         const [item] = next.splice(from, 1);
@@ -177,6 +226,12 @@ export default function WorkflowBuilder() {
             steps: wf.steps.map((r, i) => (i === idx ? { ...r, ...patch } : r)),
         });
 
+    const updateInline = (idx: number, patch: Partial<WorkflowStep>) =>
+        setWf({
+            ...wf,
+            steps: wf.steps.map((r, i) => (i === idx && r.inline ? { ...r, inline: { ...r.inline, ...patch } } : r)),
+        });
+
     const removeStep = (idx: number) => {
         const remaining = resequence(wf.steps.filter((_, i) => i !== idx));
         setWf({ ...wf, steps: remaining });
@@ -320,6 +375,26 @@ export default function WorkflowBuilder() {
                             Sync defaults
                         </Button>
                     </div>
+                    <div className="mb-3 flex items-center gap-2">
+                        <input
+                            ref={inlineFileInputRef}
+                            type="file"
+                            accept="application/json"
+                            className="hidden"
+                            onChange={onImportInline}
+                        />
+                        <Button variant="ghost" size="sm" onClick={addAdhocStep}>
+                            + Add ad-hoc step
+                        </Button>
+                        <Button
+                            variant="ghost"
+                            size="sm"
+                            loading={importingInline}
+                            onClick={() => inlineFileInputRef.current?.click()}
+                        >
+                            Import ad-hoc
+                        </Button>
+                    </div>
                     <input
                         className={`${inputClass} mb-3`}
                         placeholder="Search steps…"
@@ -367,7 +442,7 @@ export default function WorkflowBuilder() {
                         {sortedSteps.map((ref, i) => {
                             const lib = libById(ref.step_id);
                             const outs = upstreamOutputsFor(i);
-                            const script = ref.overrides?.script ?? lib?.script ?? "";
+                            const script = ref.inline?.script ?? ref.overrides?.script ?? lib?.script ?? "";
                             const wfIdx = wf.steps.indexOf(ref);
                             const isSelected = selected === i;
                             return (
@@ -405,8 +480,10 @@ export default function WorkflowBuilder() {
                                             <span className="grid h-5 w-5 place-items-center rounded border border-border font-mono text-[10px] text-text-secondary">
                                                 {i + 1}
                                             </span>
-                                            <span className="text-sm font-medium text-text-primary">{lib?.name ?? ref.step_id}</span>
-                                            {lib && <ShellBadge interpreter={lib.interpreter} />}
+                                            <span className="text-sm font-medium text-text-primary">{ref.inline?.name ?? lib?.name ?? ref.step_id}</span>
+                                            {ref.inline && <ShellBadge interpreter={ref.inline.interpreter} />}
+                                            {lib && !ref.inline && <ShellBadge interpreter={lib.interpreter} />}
+                                            {ref.inline && <AdhocBadge />}
                                         </div>
                                         <pre className="max-h-16 overflow-hidden text-ellipsis whitespace-pre-wrap rounded border border-border bg-surface-2 p-2 font-mono text-xs text-text-secondary">
                                             {script.slice(0, 200)}
@@ -439,27 +516,69 @@ export default function WorkflowBuilder() {
                                     Step {selected + 1} · Inspector
                                 </div>
                                 <div className="flex items-center gap-2">
-                                    {selectedLib && <ShellBadge interpreter={selectedLib.interpreter} />}
-                                    <h2 className="text-sm font-bold text-text-primary">{selectedLib?.name ?? selectedRef.step_id}</h2>
+                                    {selectedRef.inline && <ShellBadge interpreter={selectedRef.inline.interpreter} />}
+                                    {selectedLib && !selectedRef.inline && <ShellBadge interpreter={selectedLib.interpreter} />}
+                                    {selectedRef.inline && <AdhocBadge />}
+                                    <h2 className="text-sm font-bold text-text-primary">{selectedRef.inline?.name ?? selectedLib?.name ?? selectedRef.step_id}</h2>
                                 </div>
                             </div>
 
-                            <div className="border-b border-border pb-4">
-                                <label className="mb-1 block text-xs uppercase text-text-secondary">Command</label>
-                                <textarea
-                                    className={`${inputClass} h-32 font-mono text-xs`}
-                                    value={selectedRef.overrides?.script ?? selectedLib?.script ?? ""}
-                                    onChange={(e) =>
-                                        updateRef(selectedIdxInWf, {
-                                            overrides: { ...selectedRef.overrides, script: e.target.value },
-                                        })
-                                    }
-                                />
-                                <p className="mt-1 text-xs text-text-secondary">
-                                    Write <code className="text-signal">KEY=value</code> to <code className="text-signal">$WORKFLOW_ENV</code> to expose
-                                    it to later steps.
-                                </p>
-                            </div>
+                            {selectedRef.inline ? (
+                                <div className="space-y-4 border-b border-border pb-4">
+                                    <div>
+                                        <label className="mb-1 block text-xs uppercase text-text-secondary">Name</label>
+                                        <input
+                                            className={inputClass}
+                                            value={selectedRef.inline.name}
+                                            onChange={(e) => updateInline(selectedIdxInWf, { name: e.target.value })}
+                                        />
+                                    </div>
+                                    <div>
+                                        <label className="mb-1 block text-xs uppercase text-text-secondary">Interpreter</label>
+                                        <select
+                                            className={inputClass}
+                                            value={selectedRef.inline.interpreter}
+                                            onChange={(e) =>
+                                                updateInline(selectedIdxInWf, {
+                                                    interpreter: e.target.value as WorkflowStep["interpreter"],
+                                                })
+                                            }
+                                        >
+                                            <option value="bash">bash</option>
+                                            <option value="powershell">powershell</option>
+                                        </select>
+                                    </div>
+                                    <div>
+                                        <label className="mb-1 block text-xs uppercase text-text-secondary">Command</label>
+                                        <textarea
+                                            className={`${inputClass} h-32 font-mono text-xs`}
+                                            value={selectedRef.inline.script}
+                                            onChange={(e) => updateInline(selectedIdxInWf, { script: e.target.value })}
+                                        />
+                                        <p className="mt-1 text-xs text-text-secondary">
+                                            Write <code className="text-signal">KEY=value</code> to <code className="text-signal">$WORKFLOW_ENV</code> to
+                                            expose it to later steps. Outputs are derived automatically on save.
+                                        </p>
+                                    </div>
+                                </div>
+                            ) : (
+                                <div className="border-b border-border pb-4">
+                                    <label className="mb-1 block text-xs uppercase text-text-secondary">Command</label>
+                                    <textarea
+                                        className={`${inputClass} h-32 font-mono text-xs`}
+                                        value={selectedRef.overrides?.script ?? selectedLib?.script ?? ""}
+                                        onChange={(e) =>
+                                            updateRef(selectedIdxInWf, {
+                                                overrides: { ...selectedRef.overrides, script: e.target.value },
+                                            })
+                                        }
+                                    />
+                                    <p className="mt-1 text-xs text-text-secondary">
+                                        Write <code className="text-signal">KEY=value</code> to <code className="text-signal">$WORKFLOW_ENV</code> to expose
+                                        it to later steps.
+                                    </p>
+                                </div>
+                            )}
 
                             {(selectedLib?.declared_inputs ?? []).length > 0 && (
                                 <div className="border-b border-border pb-4">