* fix: use HasSchema check in DetermineElementType to prevent empty records
When parsing JSON arrays containing objects without a predefined schema,
`DetermineElementType()` was creating a `VariableType` with an empty
(non-null) schema via `targetType.Schema?.Select(...) ?? []`. This caused
`ParseRecord` to take the schema-based parsing path, iterating over zero
schema fields and silently discarding all JSON properties.
The fix checks `targetType.HasSchema` and falls back to
`VariableType.RecordType` (which has `Schema = null`) when no schema is
defined, ensuring `ParseRecord` takes the dynamic `ParseValues()` path
that preserves all JSON properties.
Closes#4195
* test: add regression tests for schema-less JSON array-of-objects parsing (#4195)
Add two regression tests to JsonDocumentExtensionsTests:
1. ParseRecord_ObjectWithArrayOfObjects_NoSchema_PreservesNestedProperties
- Parses a JSON object containing an array of objects using
VariableType.RecordType (no schema) and verifies that nested
object properties (name, role) are preserved in each element.
- This is the exact scenario from issue #4195 where objects in
arrays were being returned as empty dictionaries.
2. ParseList_ArrayOfObjects_NoSchema_PreservesProperties
- Parses a JSON array of objects directly via ParseList with
VariableType.ListType (no schema) and verifies all properties
are preserved.
Both tests follow the existing Arrange/Act/Assert pattern and would
have failed before the DetermineElementType() fix (empty dictionaries
instead of populated ones).
* fix: prevent doubled tool_call arguments in MESSAGES_SNAPSHOT
When streaming with client-side tools, some providers send a full-
arguments replay after the streaming deltas complete. The `_emit_tool_call`
function unconditionally appends every arguments delta to the internal
`flow.tool_calls_by_id` tracking dictionary via `+=`. When the replay
contains the exact same complete arguments string that was already
accumulated from prior deltas, the arguments get doubled (e.g.,
`{"todoText":"buy groceries"}{"todoText":"buy groceries"}`).
This causes `MESSAGES_SNAPSHOT` events to contain invalid doubled JSON in
`tool_calls[].function.arguments`, breaking any client or middleware that
relies on snapshots for state reconstruction.
The fix adds a guard (mirroring the existing duplicate guard in
`_emit_text`) that detects when the incoming delta exactly equals the
already-accumulated arguments string, indicating a full-arguments replay
rather than an incremental delta. In this case the append is skipped,
preventing the doubling.
The `ToolCallArgsEvent` deltas are still emitted correctly for real-time
streaming — only the internal snapshot accumulator is guarded.
Fixes#4194
* fix: move duplicate check before event emission + add test
Address Copilot review feedback:
1. Move duplicate full-arguments replay detection BEFORE emitting
ToolCallArgsEvent, for consistency with _emit_text() which returns
early without emitting any events on replay detection.
2. Add test_emit_tool_call_skips_duplicate_full_arguments_replay() to
verify the duplicate detection behavior for tool call arguments,
matching the existing test pattern for text content.
L. Elaine DazzioandGitHub