diff --git a/.changeset/19900-schedule-caller-param-keys.md b/.changeset/19900-schedule-caller-param-keys.md
new file mode 100644
index 00000000000..5361d7a9227
--- /dev/null
+++ b/.changeset/19900-schedule-caller-param-keys.md
@@ -0,0 +1,14 @@
+---
+'@objectstack/trigger-schedule': patch
+'@objectstack/spec': patch
+---
+
+A scheduled run no longer skips a screen whose field is named `schedule`, `jobId` or `flowName` (#19900).
+
+The schedule trigger starts each run with three seeds of its own in `params` — `jobId`, `flowName` and `schedule` — and there is no caller behind the run. It stated nothing about that, so a `screen` node's headless verdict inferred who supplied each field from `params`, read those three seeds as the caller's answers, and continued past a screen whose field shared one of the names: the run completed with the trigger's value (for `schedule`, the cron descriptor) as the answer.
+
+The trigger now sets `AutomationContext.callerParamKeys: []` — "the caller supplied nothing" — which the verdict reads instead of inferring. A screen in a scheduled flow pauses, whatever its fields are named. The three seeds stay in `params`; flows that read them are unaffected.
+
+`@objectstack/spec`: the `callerParamKeys` TSDoc now names the schedule trigger as a producer that states the empty list, and no longer lists it among the producers that leave the key absent. No type changes.
+
+This supersedes one sentence of the `callerParamKeys` entry (#19846): the schedule trigger no longer leaves the key absent. Record-change, time-relative and webhook triggers still do.
diff --git a/content/docs/automation/flows.mdx b/content/docs/automation/flows.mdx
index fcf3decce85..244a5e46ec4 100644
--- a/content/docs/automation/flows.mdx
+++ b/content/docs/automation/flows.mdx
@@ -957,9 +957,13 @@ a column named like one of the fields and including when a field is named like
 one of the seeded id keys. ⛔ `waitForInput: false` remains the wrong tool for
 the headless case: it skips the form for interactive users too.
 
-A run started any other way — a record-change, schedule, time-relative or
-webhook trigger, a `subflow` or `map` child, or code calling the engine directly
-— carries no such list, and the screen falls back to inferring the caller's keys
+A scheduled run has no caller, and the schedule trigger states exactly that —
+an empty list — so its own `jobId`, `flowName` and `schedule` params never
+answer a screen field: a screen in a scheduled flow pauses.
+
+A run started any other way — a record-change, time-relative or webhook
+trigger, a `subflow` or `map` child, or code calling the engine directly —
+carries no such list, and the screen falls back to inferring the caller's keys
 from the bag. That inference does not treat a key as the caller's when it is
 named `recordId` or `<object>Id`, when its value equals what the bag carries
 under `recordId` or `<object>Id` or the record's `id`, or when the subject
diff --git a/packages/services/service-automation/src/screen-input-contract.ts b/packages/services/service-automation/src/screen-input-contract.ts
index be5c361d497..ba76f1f7367 100644
--- a/packages/services/service-automation/src/screen-input-contract.ts
+++ b/packages/services/service-automation/src/screen-input-contract.ts
@@ -280,10 +280,11 @@ export interface HeadlessScreenContext {
  *
  * ## Absent: the inference, kept for producers that state nothing
  *
- * A record-change, schedule, time-relative or webhook trigger, a `subflow` /
- * `map` child run, or code calling the engine directly carries no signal, and
- * for those the verdict below still infers — unchanged, and failing toward a
- * pause.
+ * A record-change, time-relative or webhook trigger, a `subflow` / `map` child
+ * run, or code calling the engine directly carries no signal, and for those the
+ * verdict below still infers — unchanged, and failing toward a pause. (The
+ * schedule trigger has no caller and states `[]`, #19900, so its `jobId` /
+ * `flowName` / `schedule` seeds never reach the inference.)
  *
  * This distinction is the whole safety story of {@link judgeHeadlessScreen},
  * because the params bag a flow action reaches the engine with is NOT the
diff --git a/packages/spec/src/contracts/automation-context-caller-param-keys.pin.test.ts b/packages/spec/src/contracts/automation-context-caller-param-keys.pin.test.ts
index 88567935f29..1cad94512f7 100644
--- a/packages/spec/src/contracts/automation-context-caller-param-keys.pin.test.ts
+++ b/packages/spec/src/contracts/automation-context-caller-param-keys.pin.test.ts
@@ -13,7 +13,8 @@
  *     not a bag of values, and not a boolean per key.
  *  2. **Additive.** A context literal without it still type-checks, so no
  *     existing `IAutomationService.execute` caller moves, and an absent key is
- *     what every producer other than the two doors sends.
+ *     what every producer other than the two doors and the schedule trigger
+ *     (which states `[]`, #19900) sends.
  *  3. **An empty list is a legal value** — "the caller supplied nothing" — and
  *     it is a different value from an absent key.
  *
diff --git a/packages/spec/src/contracts/automation-service.ts b/packages/spec/src/contracts/automation-service.ts
index 9d375e34343..4e5fd3fd473 100644
--- a/packages/spec/src/contracts/automation-service.ts
+++ b/packages/spec/src/contracts/automation-service.ts
@@ -173,8 +173,13 @@ export interface AutomationContext {
      * a client that mirrors the row id into `params.recordId` is addressing the
      * row, not answering a question the flow asks.
      *
+     * One producer with no caller at all states the empty list: the schedule
+     * trigger (`ScheduleTrigger` in `@objectstack/trigger-schedule`, #19900).
+     * Its `jobId`, `flowName` and `schedule` keys in {@link params} are its own
+     * seeds, so none of them answers a question the flow asks.
+     *
      * Absent means the producer does not state provenance: a record-change,
-     * schedule, time-relative or webhook trigger, a `subflow` or `map` child run
+     * time-relative or webhook trigger, a `subflow` or `map` child run
      * (those two nodes drop the parent's list from the child context, because it
      * describes the PARENT's bag), or code calling `execute` directly. Its
      * consumer, the `screen` node's headless verdict in
diff --git a/packages/triggers/trigger-schedule/src/schedule-caller-param-keys-e2e.test.ts b/packages/triggers/trigger-schedule/src/schedule-caller-param-keys-e2e.test.ts
new file mode 100644
index 00000000000..24d12a4ffb3
--- /dev/null
+++ b/packages/triggers/trigger-schedule/src/schedule-caller-param-keys-e2e.test.ts
@@ -0,0 +1,169 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#19900] A scheduled run's platform seeds never answer a screen field.
+ *
+ * The schedule trigger starts a run with three seeds in `params` — `jobId`,
+ * `flowName` and `schedule` — and there is no caller behind it at all. A
+ * `screen` node on that headless run asks whether the caller already answered
+ * each of its fields (`judgeHeadlessScreen` in `@objectstack/service-automation`).
+ * With no statement from the producer, that answer is INFERRED from `params`,
+ * and the inference can only rule out the row-id and record seeds the other
+ * doors write: the schedule trigger's three names read as the caller's own
+ * answers, so a screen with a required field named `schedule` was skipped and
+ * the run completed with the cron descriptor as the "answer".
+ *
+ * The producer now states it: `callerParamKeys: []` — "the caller supplied
+ * nothing", which the verdict reads instead of inferring (#19846).
+ *
+ * The rig is the one `schedule-runas-e2e.test.ts` uses: the REAL
+ * `ScheduleTrigger` bound through the REAL `AutomationEngine`, the job fired by
+ * hand in place of the cron tick. The result read is the one the engine
+ * returned to the trigger's own callback — not a hand-made context.
+ *
+ * ⚠️ `@objectstack/service-automation` resolves to its `dist/` here (no alias:
+ * `KNOWN_UNALIASED_TEST_IMPORTS` in `scripts/check-test-source-alias.mjs`), so
+ * the engine half is the built one. The half this file pins — the context the
+ * trigger builds — is `./schedule-trigger.js`, read from source.
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { AutomationEngine, installBuiltinNodes } from '@objectstack/service-automation';
+import type { AutomationContext, JobSchedule, JobHandler } from '@objectstack/spec/contracts';
+import { ScheduleTrigger } from './schedule-trigger.js';
+import { withScheduledWorkOn } from './deployment-switch.test-support.js';
+
+function silentLogger(): any {
+  const l: any = { info() {}, warn() {}, error() {}, debug() {} };
+  l.child = () => l;
+  return l;
+}
+const flush = () => new Promise<void>((r) => setTimeout(r, 0));
+
+/** Fake IJobService slice with a deterministic `fire()` standing in for the cron tick. */
+function fakeJobService() {
+  const jobs = new Map<string, { schedule: JobSchedule; handler: JobHandler }>();
+  return {
+    service: {
+      async schedule(name: string, schedule: JobSchedule, handler: JobHandler) {
+        jobs.set(name, { schedule, handler });
+      },
+      async cancel(name: string) {
+        jobs.delete(name);
+      },
+    },
+    has: (name: string) => jobs.has(name),
+    fire: async (name: string, jobId = 'tick-1') => {
+      await jobs.get(name)?.handler({ jobId } as never);
+    },
+  };
+}
+
+type Field = { name: string; label: string; type: string; required?: boolean };
+
+const CRON: JobSchedule = { type: 'cron', expression: '0 2 * * *' } as JobSchedule;
+
+/**
+ * `start → screen_1 → end` on a `type: 'schedule'` flow, each screen field an
+ * `isInput` variable — so the seed of the same name IS bound into it, which is
+ * the only way the skip could happen.
+ */
+function scheduledScreenFlow(name: string, fields: Field[]) {
+  return {
+    name,
+    label: name,
+    type: 'schedule',
+    runAs: 'system',
+    status: 'active',
+    version: 1,
+    variables: fields.map((f) => ({ name: f.name, type: 'text', isInput: true, isOutput: true })),
+    nodes: [
+      { id: 'start', type: 'start', label: 'Start', config: { schedule: CRON } },
+      { id: 'screen_1', type: 'screen', label: 'Ask', config: { fields } },
+      { id: 'end', type: 'end', label: 'End' },
+    ],
+    edges: [
+      { id: 'e1', source: 'start', target: 'screen_1', type: 'default' },
+      { id: 'e2', source: 'screen_1', target: 'end', type: 'default' },
+    ],
+  } as never;
+}
+
+/**
+ * Bind the flow through the real trigger, fire one tick, and hand back what
+ * the trigger passed to the engine and what the engine answered it with.
+ */
+async function fireOnce(flowName: string, fields: Field[]) {
+  const engine = new AutomationEngine(silentLogger());
+  installBuiltinNodes(engine, { logger: silentLogger(), getService: () => undefined } as never);
+  const execute = vi.spyOn(engine, 'execute');
+  engine.registerFlow(flowName, scheduledScreenFlow(flowName, fields));
+  const job = fakeJobService();
+  engine.registerTrigger(new ScheduleTrigger(() => job.service, silentLogger()));
+  await flush(); // let ScheduleTrigger.start() schedule the job
+
+  const jobName = `flow-schedule:${flowName}`;
+  expect(job.has(jobName), 'the flow was not bound to the schedule trigger').toBe(true);
+  await job.fire(jobName, 'tick-42');
+
+  expect(execute).toHaveBeenCalledTimes(1);
+  const context = execute.mock.calls[0][1] as AutomationContext;
+  const result = await execute.mock.results[0].value;
+  return { engine, context, result };
+}
+
+// [#17396] The switch is OFF by default in every posture; nothing binds without it.
+withScheduledWorkOn('single');
+
+describe('[#19900] a scheduled run\'s platform seeds never answer a screen field', () => {
+  it('the trigger states that its run has no caller: `callerParamKeys` is an empty list', async () => {
+    const { context } = await fireOnce('nightly_ask', [
+      { name: 'schedule', label: 'Schedule', type: 'text', required: true },
+    ]);
+    // The seeds are still there — flows read them — they are just not a caller's.
+    expect(context.params).toMatchObject({ jobId: 'tick-42', flowName: 'nightly_ask', schedule: CRON });
+    expect(context.callerParamKeys).toEqual([]);
+  });
+
+  it.each(['schedule', 'jobId', 'flowName'])(
+    'a required screen field named `%s` pauses the run instead of taking the seed as its answer',
+    async (seed) => {
+      const { engine, result } = await fireOnce('nightly_ask', [
+        { name: seed, label: seed, type: 'text', required: true },
+      ]);
+      // One object, so a skip prints what the run completed WITH.
+      expect(result).toMatchObject({ status: 'paused', screen: { nodeId: 'screen_1' } });
+      expect(engine.listSuspendedRuns()).toEqual([
+        expect.objectContaining({ flowName: 'nightly_ask', nodeId: 'screen_1' }),
+      ]);
+    },
+  );
+
+  it('an all-optional screen named after every seed pauses too — the seeds do not "drive" it', async () => {
+    const { result } = await fireOnce('nightly_ask', [
+      { name: 'schedule', label: 'Schedule', type: 'text' },
+      { name: 'jobId', label: 'Job', type: 'text' },
+      { name: 'flowName', label: 'Flow', type: 'text' },
+    ]);
+    expect(result).toMatchObject({ status: 'paused', screen: { nodeId: 'screen_1' } });
+  });
+
+  it('control: the same flow on the same engine continues when a context names `schedule` as a caller key', async () => {
+    // The pause above is the signal's doing, not "a screen in a schedule flow
+    // always pauses": a door that states real caller keys still answers it.
+    const engine = new AutomationEngine(silentLogger());
+    installBuiltinNodes(engine, { logger: silentLogger(), getService: () => undefined } as never);
+    engine.registerFlow('nightly_ask', scheduledScreenFlow('nightly_ask', [
+      { name: 'schedule', label: 'Schedule', type: 'text', required: true },
+    ]));
+    const result = await engine.execute('nightly_ask', {
+      event: 'schedule',
+      params: { jobId: 'tick-42', flowName: 'nightly_ask', schedule: '0 2 * * *' },
+      callerParamKeys: ['schedule'],
+    });
+    expect(result.status).not.toBe('paused');
+    expect(result.success).toBe(true);
+    expect(result.output).toMatchObject({ schedule: '0 2 * * *' });
+    expect(engine.listSuspendedRuns()).toEqual([]);
+  });
+});
diff --git a/packages/triggers/trigger-schedule/src/schedule-trigger.ts b/packages/triggers/trigger-schedule/src/schedule-trigger.ts
index fecaf492503..5d67f8394de 100644
--- a/packages/triggers/trigger-schedule/src/schedule-trigger.ts
+++ b/packages/triggers/trigger-schedule/src/schedule-trigger.ts
@@ -808,6 +808,15 @@ export class ScheduleTrigger implements FlowTrigger {
                         flowName: binding.flowName,
                         schedule,
                     },
+                    // [#19900] A tick has no caller, so no key above is a
+                    // caller's answer — all three are this trigger's own seeds.
+                    // Stated rather than left to inference: a `screen` node's
+                    // headless verdict reads this list when present (#19846),
+                    // and without it inferred `jobId` / `flowName` / `schedule`
+                    // as supplied, skipping a screen whose field shared a name.
+                    // ⛔ An empty list, never an absent key — absent means
+                    // "not stated", and the inference answers that.
+                    callerParamKeys: [],
                 };
                 await callback(ctx);
                 if (key) await this.settleDispatch(binding.flowName, key, 'succeeded');