test(chat): cover referenced-chat resolver and transcript budgeting

Add unit tests for role-specific turn extraction in the resolver and for
the transcript renderer: full rendering within budget, dropping oldest
turns with a marker, partial-tail fill of an overflowing turn, and
multi-chat tagging.

surfsense_backend/tests/unit/agents/chat/runtime/referenced_chat_context/test_resolver.py

@@ -0,0 +1,44 @@
+"""Tests for referenced-chat message text extraction."""
+
+from __future__ import annotations
+
+import pytest
+
+from app.agents.chat.runtime.referenced_chat_context.resolver import _visible_text
+from app.db import NewChatMessage, NewChatMessageRole
+
+pytestmark = pytest.mark.unit
+
+
+def _message(role: NewChatMessageRole, content: object) -> NewChatMessage:
+    return NewChatMessage(role=role, content=content)
+
+
+def test_assistant_text_drops_reasoning_and_keeps_visible_text() -> None:
+    message = _message(
+        NewChatMessageRole.ASSISTANT,
+        [
+            {"type": "thinking", "thinking": "private"},
+            {"type": "text", "text": "visible answer"},
+        ],
+    )
+
+    assert _visible_text(message) == "visible answer"
+
+
+def test_user_text_drops_images_and_keeps_text() -> None:
+    message = _message(
+        NewChatMessageRole.USER,
+        [
+            {"type": "text", "text": "look at this"},
+            {"type": "image", "image": "data:image/png;base64,AAA"},
+        ],
+    )
+
+    assert _visible_text(message) == "look at this"
+
+
+def test_plain_string_content_is_returned_as_is() -> None:
+    message = _message(NewChatMessageRole.USER, "just text")
+
+    assert _visible_text(message) == "just text"

surfsense_backend/tests/unit/agents/chat/runtime/referenced_chat_context/test_transcript.py

@@ -0,0 +1,127 @@
+"""Tests for referenced-chat transcript rendering and token budgeting."""
+
+from __future__ import annotations
+
+import pytest
+
+from app.agents.chat.runtime.referenced_chat_context import (
+    ReferencedChat,
+    render_referenced_chats_block,
+)
+from app.agents.chat.runtime.referenced_chat_context import transcript as transcript_mod
+from app.agents.chat.runtime.referenced_chat_context.models import ReferencedChatTurn
+
+pytestmark = pytest.mark.unit
+
+
+def _chat(thread_id: int, title: str, turns: list[tuple[str, str]]) -> ReferencedChat:
+    return ReferencedChat(
+        thread_id=thread_id,
+        title=title,
+        turns=[ReferencedChatTurn(role=role, text=text) for role, text in turns],
+    )
+
+
+def test_returns_none_when_no_chats() -> None:
+    assert render_referenced_chats_block([]) is None
+
+
+def test_renders_header_chat_tag_and_turns_in_order() -> None:
+    block = render_referenced_chats_block(
+        [_chat(7, "Roadmap", [("user", "hi"), ("assistant", "hello")])]
+    )
+
+    assert block is not None
+    assert block.startswith("<referenced_chat_context>")
+    assert block.endswith("</referenced_chat_context>")
+    assert '<chat thread_id="7" title="Roadmap">' in block
+    # Chronological order is preserved.
+    assert block.index("user: hi") < block.index("assistant: hello")
+    assert "</chat>" in block
+
+
+def test_escapes_special_characters_in_title() -> None:
+    block = render_referenced_chats_block([_chat(1, '<a> & "b"', [("user", "q")])])
+
+    assert block is not None
+    assert 'title="&lt;a&gt; &amp; &quot;b&quot;">' in block
+    # Raw, unescaped title must never reach the attribute.
+    assert '<a> & "b"' not in block
+
+
+def test_budget_keeps_recent_turns_and_marks_truncation(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    # Each line below is ~10 chars; a 25-char budget fits two short lines.
+    monkeypatch.setattr(transcript_mod, "_MAX_CHARS_PER_REFERENCE", 25)
+
+    block = render_referenced_chats_block(
+        [
+            _chat(
+                1,
+                "T",
+                [("user", "aaaa"), ("assistant", "bbbb"), ("user", "cccc")],
+            )
+        ]
+    )
+
+    assert block is not None
+    # Oldest turn dropped, marker prepended, remaining turns chronological.
+    assert transcript_mod._TRUNCATION_MARKER in block
+    assert "user: aaaa" not in block
+    assert block.index("assistant: bbbb") < block.index("user: cccc")
+
+
+def test_oversized_single_turn_is_partially_filled_to_use_budget(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(transcript_mod, "_MAX_CHARS_PER_REFERENCE", 40)
+
+    block = render_referenced_chats_block(
+        [_chat(1, "T", [("assistant", "x" * 500)])]
+    )
+
+    assert block is not None
+    # The turn is too big to keep whole, so its tail fills the budget with a
+    # role label, a mid-turn "…" marker, and a block-level truncation marker.
+    assert "assistant: \u2026" in block
+    assert transcript_mod._TRUNCATION_MARKER in block
+    assert "x" * 500 not in block
+    # The partial turn line never exceeds the budget.
+    turn_line = next(
+        line for line in block.splitlines() if line.startswith("assistant: ")
+    )
+    assert len(turn_line) <= 40
+
+
+def test_overflowing_older_turn_fills_remaining_budget(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(transcript_mod, "_MAX_CHARS_PER_REFERENCE", 40)
+
+    block = render_referenced_chats_block(
+        [_chat(1, "T", [("user", "y" * 100), ("assistant", "zzzz")])]
+    )
+
+    assert block is not None
+    # Newest turn kept whole; leftover budget filled with the older turn's tail
+    # instead of dropping it entirely.
+    assert "assistant: zzzz" in block
+    assert "user: \u2026" in block
+    assert transcript_mod._TRUNCATION_MARKER in block
+    # Chronological order: partial older turn precedes the newest turn.
+    assert block.index("user: \u2026") < block.index("assistant: zzzz")
+
+
+def test_renders_multiple_chats_each_in_own_tag() -> None:
+    block = render_referenced_chats_block(
+        [
+            _chat(1, "First", [("user", "one")]),
+            _chat(2, "Second", [("user", "two")]),
+        ]
+    )
+
+    assert block is not None
+    assert '<chat thread_id="1" title="First">' in block
+    assert '<chat thread_id="2" title="Second">' in block
+    assert block.count("</chat>") == 2