0064ff6741
## Problem
On a self-hosted instance, an AI Agent workflow action fails at run time
with an opaque model error:
```
The model returned the following errors: tools.0.custom.input_schema.properties:
Property keys should match pattern '^[a-zA-Z0-9_.-]{1,64}$'
```
This is Anthropic's validation on tool `input_schema` **property keys**.
An AI Agent's structured **Output** fields are turned into a JSON schema
and passed to the model as a tool; each output **variable name** becomes
a property key. Anthropic rejects any key that does not match
`^[a-zA-Z0-9_.-]{1,64}$` — most commonly a name containing a **space**
(e.g. `meetings brief`), but also names over 64 characters or with other
symbols.
Until now nothing validated this: `fieldsToSchema` writes
`properties[field.name]` verbatim, so a bad name only failed once the
workflow executed, with an error that gives the user no idea what to
fix. It doesn't reproduce on every instance — it depends purely on how
the workflow's output variables happen to be named.
## Fix
Introduce a single shared check,
`isValidAgentResponseSchemaPropertyKey`, and enforce it in two places:
- **Backend** — `validateAgentResponseFormat` now rejects invalid output
field names at agent **save time** with a clear `userFriendlyMessage`,
instead of letting the broken schema reach the model. This also gates
agents created via the API and re-saves of existing bad data.
- **Frontend** — the output schema builder shows an inline error on the
Variable Name field as soon as an invalid name is entered.
## Tests
- Unit test for the shared validity check (valid + invalid cases:
spaces, leading space, empty, > 64 chars, symbols, unicode).
- Unit test for `validateAgentResponseFormat` covering text/json
formats, valid names, a space in a name, an over-length name, and
reporting multiple invalid names at once.
## Notes for the reporter
The immediate unblock for an affected workflow is to rename the output
variable to remove the space (e.g. `meetings brief` → `meetings_brief`)
and retry the run. With this change the bad name is caught up front with
an explanation rather than failing mid-run.
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