diff --git a/steward/ansible/routes.py b/steward/ansible/routes.py
index ccf5fce..d88dca8 100644
--- a/steward/ansible/routes.py
+++ b/steward/ansible/routes.py
@@ -143,6 +143,35 @@ def _parse_run_params(form) -> tuple[dict | None, dict | None, str | None]:
     return (params or None), (secret_vars or None), None
 
 
+@ansible_bp.get("/playbook-options")
+@require_role(UserRole.operator)
+async def playbook_options():
+    """HTMX fragment: <option>s of playbooks in a source, to populate a playbook
+    dropdown when a source is chosen. `selected` pre-selects one (edit forms)."""
+    source_name = (request.args.get("source_name", "") or "").strip()
+    selected = (request.args.get("selected", "") or "").strip()
+    source = next((s for s in _get_sources() if s["name"] == source_name), None)
+    playbooks = src_module.discover_playbooks(source["path"]) if source else []
+    return await render_template(
+        "ansible/_playbook_options.html", playbooks=playbooks, selected=selected)
+
+
+@ansible_bp.get("/playbook-vars")
+@require_role(UserRole.operator)
+async def playbook_vars():
+    """HTMX fragment: fill-in fields for a playbook's declared variables
+    (vars/vars_prompt), loaded when a playbook is chosen from a dropdown."""
+    source_name = (request.args.get("source_name", "") or "").strip()
+    playbook_path = (request.args.get("playbook_path", "") or "").strip()
+    source = next((s for s in _get_sources() if s["name"] == source_name), None)
+    variables: list = []
+    if source and playbook_path:
+        contents = src_module.read_playbook(source["path"], playbook_path)
+        if contents is not None:
+            variables = src_module.discover_playbook_variables(contents)
+    return await render_template("ansible/_playbook_vars.html", variables=variables)
+
+
 @ansible_bp.get("/run-form/<source_name>/<path:playbook_path>")
 @require_role(UserRole.operator)
 async def run_form(source_name: str, playbook_path: str):
diff --git a/steward/hosts/routes.py b/steward/hosts/routes.py
index 95e0ab2..e689220 100644
--- a/steward/hosts/routes.py
+++ b/steward/hosts/routes.py
@@ -349,24 +349,12 @@ async def run_playbook(host_id: str):
     if playbook not in ansible_src.discover_playbooks(source["path"]):
         return f"Playbook '{playbook}' not found in source '{source_name}'", 404
 
-    # Optional params (no --limit — there's exactly one host).
-    extra_vars: list[str] = []
-    for line in (form.get("extra_vars", "") or "").splitlines():
-        line = line.strip()
-        if not line:
-            continue
-        if "=" not in line:
-            return f"Invalid extra var (expected key=value): {line!r}", 400
-        extra_vars.append(line)
-    params: dict = {}
-    if extra_vars:
-        params["extra_vars"] = extra_vars
-    tags = (form.get("tags", "") or "").strip()
-    if tags:
-        params["tags"] = tags
-    if "check" in form:
-        params["check"] = True
-    params_or_none = params or None
+    # Shared parser: discovered var__ fields → extra_vars_map, secret__ → secret_vars
+    # (unpersisted), plus tags/check. No --limit — there's exactly one host.
+    from steward.ansible.routes import _parse_run_params
+    params_or_none, secret_vars, err = _parse_run_params(form)
+    if err:
+        return err, 400
 
     run_id = str(uuid.uuid4())
     inv_content = ansible_src.host_inventory_content(host)
@@ -387,7 +375,7 @@ async def run_playbook(host_id: str):
         executor.start_run(
             current_app._get_current_object(),  # type: ignore[attr-defined]
             run_id, playbook, f"host: {host.name}", source["path"],
-            params_or_none, inv_content,
+            params_or_none, inv_content, secret_vars=secret_vars,
         )
     )
     task.add_done_callback(
diff --git a/steward/templates/ansible/_playbook_options.html b/steward/templates/ansible/_playbook_options.html
new file mode 100644
index 0000000..59a9522
--- /dev/null
+++ b/steward/templates/ansible/_playbook_options.html
@@ -0,0 +1,6 @@
+{# <option> list for a playbook <select>, populated when a source is chosen.
+   Returned by /ansible/playbook-options. `selected` pre-selects one (edit). #}
+<option value="">— choose playbook —</option>
+{% for pb in playbooks %}
+<option value="{{ pb }}" {% if pb == selected %}selected{% endif %}>{{ pb }}</option>
+{% endfor %}
diff --git a/steward/templates/ansible/_playbook_vars.html b/steward/templates/ansible/_playbook_vars.html
new file mode 100644
index 0000000..ecc611c
--- /dev/null
+++ b/steward/templates/ansible/_playbook_vars.html
@@ -0,0 +1,32 @@
+{# Discovered playbook variables as fill-in fields. Shared by the browse run
+   form, the host run form, and the schedule form. Expects `variables` (from
+   discover_playbook_variables). Rendered standalone by /ansible/playbook-vars. #}
+{% if variables %}
+<div style="margin:0.5rem 0 0.25rem;font-size:0.82rem;color:var(--text-muted);font-weight:600;">
+  Playbook variables
+</div>
+<p style="color:var(--text-dim);font-size:0.76rem;margin:0 0 0.6rem;">
+  Leave a field blank to use the playbook/inventory default. Secret fields are never stored.
+</p>
+{% for v in variables %}
+<div class="form-group">
+  <label>
+    {{ v.prompt or v.name }}
+    <span style="color:var(--text-muted);font-weight:normal;font-size:0.76rem;">
+      ({{ v.name }}{% if v.required %}, required{% endif %}{% if v.secret %}, secret{% endif %})
+    </span>
+  </label>
+  {% if v.secret %}<input type="hidden" name="secret__{{ v.name }}" value="1">{% endif %}
+  <input type="{{ 'password' if v.secret else 'text' }}"
+         name="var__{{ v.name }}"
+         {% if v.required %}required{% endif %}
+         {% if v.secret %}autocomplete="new-password"{% endif %}
+         placeholder="{% if v.secret %}(hidden){% elif v.default not in (None, '') %}default: {{ v.default }}{% else %}no default{% endif %}"
+         style="width:100%;font-family:ui-monospace,monospace;font-size:0.85rem;">
+</div>
+{% endfor %}
+{% else %}
+<p style="color:var(--text-dim);font-size:0.8rem;margin:0.25rem 0 0.6rem;">
+  No declared variables found in this playbook.
+</p>
+{% endif %}
diff --git a/steward/templates/ansible/_run_form.html b/steward/templates/ansible/_run_form.html
index 088f0f1..d706683 100644
--- a/steward/templates/ansible/_run_form.html
+++ b/steward/templates/ansible/_run_form.html
@@ -34,36 +34,7 @@
       </select>
     </div>
 
-    {% if variables %}
-    <div style="margin:0.5rem 0 0.25rem;font-size:0.82rem;color:var(--text-muted);font-weight:600;">
-      Playbook variables
-    </div>
-    <p style="color:var(--text-dim);font-size:0.76rem;margin:0 0 0.6rem;">
-      Leave a field blank to use the playbook/inventory default. Secret fields are
-      never stored.
-    </p>
-    {% for v in variables %}
-    <div class="form-group">
-      <label>
-        {{ v.prompt or v.name }}
-        <span style="color:var(--text-muted);font-weight:normal;font-size:0.76rem;">
-          ({{ v.name }}{% if v.required %}, required{% endif %}{% if v.secret %}, secret{% endif %})
-        </span>
-      </label>
-      {% if v.secret %}<input type="hidden" name="secret__{{ v.name }}" value="1">{% endif %}
-      <input type="{{ 'password' if v.secret else 'text' }}"
-             name="var__{{ v.name }}"
-             {% if v.required %}required{% endif %}
-             {% if v.secret %}autocomplete="new-password"{% endif %}
-             placeholder="{% if v.secret %}(hidden){% elif v.default not in (None, '') %}default: {{ v.default }}{% else %}no default{% endif %}"
-             style="width:100%;font-family:ui-monospace,monospace;font-size:0.85rem;">
-    </div>
-    {% endfor %}
-    {% else %}
-    <p style="color:var(--text-dim);font-size:0.8rem;margin:0.25rem 0 0.6rem;">
-      No declared variables found in this playbook.
-    </p>
-    {% endif %}
+    {% include "ansible/_playbook_vars.html" %}
 
     <details style="margin:0.25rem 0 0.75rem;">
       <summary style="cursor:pointer;font-size:0.82rem;color:var(--text-muted);">Advanced</summary>
diff --git a/steward/templates/ansible/schedules.html b/steward/templates/ansible/schedules.html
index 0fe51ee..f9c9d9e 100644
--- a/steward/templates/ansible/schedules.html
+++ b/steward/templates/ansible/schedules.html
@@ -86,7 +86,9 @@
       </div>
       <div class="form-group" style="margin-bottom:0;">
         <label>Source</label>
-        <select name="source_name" required>
+        <select name="source_name" required
+                hx-get="/ansible/playbook-options" hx-trigger="change"
+                hx-target="#sch-playbook" hx-swap="innerHTML" hx-include="this">
           <option value="">— choose source —</option>
           {% for sd in source_data %}
           <option value="{{ sd.name }}" {% if editing and editing.source_name == sd.name %}selected{% endif %}>{{ sd.name }}</option>
@@ -94,12 +96,13 @@
         </select>
       </div>
       <div class="form-group" style="margin-bottom:0;">
-        <label>Playbook path</label>
-        <input type="text" name="playbook_path" required list="playbooks"
-               value="{{ editing.playbook_path if editing else '' }}" placeholder="maintenance/docker_prune.yml">
-        <datalist id="playbooks">
-          {% for pb in all_playbooks %}<option value="{{ pb }}"></option>{% endfor %}
-        </datalist>
+        <label>Playbook</label>
+        <select name="playbook_path" id="sch-playbook" required>
+          <option value="">— choose playbook —</option>
+          {% for pb in all_playbooks %}
+          <option value="{{ pb }}" {% if editing and editing.playbook_path == pb %}selected{% endif %}>{{ pb }}</option>
+          {% endfor %}
+        </select>
       </div>
       <div class="form-group" style="margin-bottom:0;">
         <label>Target</label>
@@ -132,7 +135,8 @@
     </div>
     <div class="form-group" style="margin-top:1rem;">
       <label>Extra vars (one key=value per line)</label>
-      <textarea name="extra_vars" rows="3" placeholder="prune_volumes=false">{{ p.get('extra_vars', []) | join('\n') }}</textarea>
+      <textarea name="extra_vars" rows="3" placeholder="prune_volumes=false">{% for k, v in (p.get('extra_vars_map') or {}).items() %}{{ k }}={{ v }}
+{% endfor %}</textarea>
     </div>
     <div class="form-group" style="display:flex;align-items:center;gap:0.5rem;">
       <input type="checkbox" name="check" id="check" style="width:auto;" {% if p.get('check') %}checked{% endif %}>
diff --git a/steward/templates/hosts/detail.html b/steward/templates/hosts/detail.html
index 81217c5..50eddd9 100644
--- a/steward/templates/hosts/detail.html
+++ b/steward/templates/hosts/detail.html
@@ -109,23 +109,38 @@
     <form method="post" action="/hosts/{{ host.id }}/run-playbook" style="margin-top:0.75rem;">
       <div class="form-group">
         <label>Source</label>
-        <select name="source_name" required>
+        <select name="source_name" required
+                hx-get="/ansible/playbook-options" hx-trigger="change"
+                hx-target="#hp-playbook" hx-swap="innerHTML" hx-include="this">
+          <option value="">— choose source —</option>
           {% for s in ansible_sources %}<option value="{{ s }}">{{ s }}</option>{% endfor %}
         </select>
       </div>
       <div class="form-group">
-        <label>Playbook <span style="color:var(--text-muted);font-weight:normal;">(path within source)</span></label>
-        <input type="text" name="playbook_path" placeholder="playbooks/site.yml" required>
-      </div>
-      <div class="form-group">
-        <label>Extra vars <span style="color:var(--text-muted);font-weight:normal;">(one key=value per line)</span></label>
-        <textarea name="extra_vars" rows="2" style="width:100%;font-family:ui-monospace,monospace;font-size:0.85rem;"></textarea>
-      </div>
-      <div class="form-group">
-        <label style="display:flex;align-items:center;gap:0.5rem;font-weight:normal;">
-          <input type="checkbox" name="check"> Dry-run (--check --diff)
-        </label>
+        <label>Playbook</label>
+        <select name="playbook_path" id="hp-playbook" required
+                hx-get="/ansible/playbook-vars" hx-trigger="change"
+                hx-target="#hp-vars" hx-swap="innerHTML" hx-include="closest form">
+          <option value="">— choose a source first —</option>
+        </select>
       </div>
+      <div id="hp-vars"></div>
+      <details style="margin:0.25rem 0 0.75rem;">
+        <summary style="cursor:pointer;font-size:0.82rem;color:var(--text-muted);">Advanced</summary>
+        <div class="form-group" style="margin-top:0.6rem;">
+          <label>Extra vars <span style="color:var(--text-muted);font-weight:normal;">(one key=value per line)</span></label>
+          <textarea name="extra_vars" rows="2" style="width:100%;font-family:ui-monospace,monospace;font-size:0.85rem;"></textarea>
+        </div>
+        <div class="form-group">
+          <label>Tags <span style="color:var(--text-muted);font-weight:normal;">(--tags)</span></label>
+          <input type="text" name="tags" placeholder="deploy,config">
+        </div>
+        <div class="form-group">
+          <label style="display:flex;align-items:center;gap:0.5rem;font-weight:normal;">
+            <input type="checkbox" name="check"> Dry-run (--check --diff)
+          </label>
+        </div>
+      </details>
       <button type="submit" class="btn btn-sm">Run playbook</button>
     </form>
   </details>