Flow inputs carry an origin hint, run or panel

The Inputs editor and the canvas label show it, and the run forms leave
panel inputs out.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx

docs/concepts/flows.md

@@ -96,13 +96,18 @@ Declare messages supplied by dashboard controls, the API or run parameters as
 the flow's **Inputs**. Give live inputs a starting value:
 
 ```json
-{"inputs": [{"spec": {"name": "setpoint", "dtype": "float"}, "initial": 21.0}]}
+{"inputs": [{"spec": {"name": "setpoint", "dtype": "float"}, "initial": 21.0, "origin": "panel"}]}
 ```
 
 This seeds `house.setpoint` in flow `house` if it has no value yet. Later
 publications replace it. Batch inputs are run parameters, and batch outputs
 select the run's result. See [Where a node's values come from](values.md).
 
+`origin` says what writes an input: `run` (the default) for a parameter a run
+passes in, `panel` for a dashboard or panel control. The canvas labels each
+input with it, and the run form leaves panel inputs out, so a run keeps their
+starting value. The engine treats both the same.
+
 ## Drafts and publishing
 
 - **Saving** stores a draft; the engine keeps running the published version.