docs: name the schedule trigger as a producer that states callerParamKeys: []

The callerParamKeys TSDoc, the screen verdict's docblock, the flows guide
and the pending caller-param-keys changeset each listed the schedule trigger
among the producers that leave the key absent. It now states the empty list,
so each statement is corrected. Adds this change's own changeset.

Claude-Session: https://claude.ai/code/session_01Evb5jFDZGKQE9KG4jbMfMF
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/19846-automation-caller-param-keys.md

@@ -12,7 +12,7 @@ A screen whose fields the run's caller already supplied continues without pausin
 
 **What the key says.** The keys of the caller's own `params`, recorded before the door seeds anything. An empty array means the caller supplied nothing; an absent key means the producer does not say.
 
-**Who fills it.** The action door (`dispatchFlowAction`: `POST /api/v1/actions/...` and MCP `run_action`) and the trigger door (`buildAutomationContext`: `POST /api/v1/automation/:name/trigger`, the legacy `POST /api/v1/automation/trigger/:name`, and a declarative `type: 'flow'` endpoint). Record-change, schedule, time-relative and webhook triggers, and code calling `execute` directly, leave it absent. `subflow` and `map` nodes drop the parent's list from the child run's context, because it describes the parent's bag.
+**Who fills it.** The action door (`dispatchFlowAction`: `POST /api/v1/actions/...` and MCP `run_action`) and the trigger door (`buildAutomationContext`: `POST /api/v1/automation/:name/trigger`, the legacy `POST /api/v1/automation/trigger/:name`, and a declarative `type: 'flow'` endpoint). Record-change, time-relative and webhook triggers, and code calling `execute` directly, leave it absent; the schedule trigger, which has no caller, states an empty list (#19900). `subflow` and `map` nodes drop the parent's list from the child run's context, because it describes the parent's bag.
 
 **What the screen does with it.** When the key is present, a field is caller-supplied when its name is in the list and `params` holds a value for it; the inference is not consulted. A present value that is not an array names nothing, so the screen pauses. When the key is absent, the inference from #15787 applies unchanged.
 

.changeset/19900-schedule-caller-param-keys.md

@@ -0,0 +1,12 @@
+---
+'@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.

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

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

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.
  *

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