Python: Fix structured value parsing for split text chunks

[t-anjan]

Structured response parsing currently uses the public text property, which inserts spaces between TextContent chunks inside a Message. That can corrupt split JSON structured outputs while leaving normal display text behavior correct.

This change keeps Message.text unchanged and uses a structured-output-only text path that concatenates text chunks without synthetic spaces before parsing ChatResponse.value and AgentResponse.value.

Tests:

• cd python && uv run pytest packages/core/tests/core/test_types.py
• cd python && uv run ruff check packages/core/agent_framework/_types.py packages/core/tests/core/test_types.py
• git diff --check

[Copilot]

Pull request overview

Fixes structured-output parsing for ChatResponse.value and AgentResponse.value by avoiding the synthetic spaces introduced by Message.text when a message contains multiple text Content chunks (which can corrupt split JSON). The public Message.text/Response.text behavior remains unchanged for display.

Changes:

• Added structured-output-only text assembly helpers that concatenate text chunks without inserting spaces.
• Updated ChatResponse.value and AgentResponse.value to parse structured output from the structured-only text path instead of self.text.
• Added regression tests covering split JSON across text chunks while preserving Message.text spacing behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
python/packages/core/agent_framework/_types.py	Adds structured-only text helpers and switches structured parsing to use them (avoids Message.text synthetic spacing).
python/packages/core/tests/core/test_types.py	Adds tests ensuring split structured JSON parses correctly without changing Message.text/response.text.

[github-actions]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework
_types.py	1222	97	92%	61, 70–71, 125, 130, 149, 151, 155, 159, 161, 163, 165, 183, 187, 213, 235, 240, 245, 249, 279, 703–704, 863–864, 1299, 1371, 1406, 1426, 1436, 1488, 1620–1622, 1907–1912, 1937, 1992, 1997, 2007, 2015, 2022–2026, 2044, 2117, 2130, 2135, 2252, 2275, 2531, 2555, 2654, 2830–2831, 2933, 3162, 3215, 3234, 3273, 3284, 3286–3290, 3292, 3295–3303, 3313, 3402, 3539, 3544, 3549, 3554, 3558, 3644–3646, 3675, 3763–3767
TOTAL	44497	5346	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
8818	33 💤	0 ❌	0 🔥	2m 7s ⏱️