Merge remote-tracking branch 'origin/main' into feature/rag

# Conflicts:
#	studio/backend/core/inference/llama_cpp.py
#	studio/backend/routes/__init__.py
#	studio/backend/routes/inference.py
#	studio/frontend/package.json
#	studio/frontend/src/components/assistant-ui/sources.tsx
#	studio/frontend/src/components/assistant-ui/thread.tsx
#	studio/frontend/src/features/chat/api/chat-adapter.ts
#	studio/frontend/src/features/chat/chat-settings-sheet.tsx
#	studio/frontend/src/features/chat/shared-composer.tsx
#	studio/frontend/src/features/chat/stores/chat-runtime-store.ts
#	studio/frontend/src/features/settings/settings-dialog.tsx

tests/python/test_construct_chat_template_validation.py

@@ -0,0 +1,77 @@
+"""Negative-path validation tests for unsloth.chat_templates.construct_chat_template.
+
+Regression coverage for the str.find() / regex no-match guards added in
+PR #5763 follow-up: missing placeholders or unrecoverable two-example
+structures must raise RuntimeError with a clear message, not IndexError
+or AttributeError, and must never silently drop the last character via
+s[:-1].
+
+Uses a minimal fake tokenizer so the cases run on CPU-only CI without
+HF_TOKEN and without downloading a gated model. The validation paths
+exercised here fail before construct_chat_template reaches any heavy
+tokenizer interaction, so the stub stays small.
+"""
+
+import pytest
+
+from unsloth.chat_templates import construct_chat_template
+
+
+class _FakeTokenizer:
+    """Minimum surface construct_chat_template touches before the
+    validation guards fire."""
+
+    name_or_path = "fake/tokenizer"
+    eos_token = "</s>"
+
+    def get_vocab(self):
+        return {"</s>": 0}
+
+
+@pytest.mark.parametrize(
+    "template, expected_in_message",
+    [
+        ("only {INPUT} here, no output marker", "{OUTPUT}"),
+        ("only {OUTPUT} here, no input marker", "{INPUT}"),
+        ("neither sentinel here, just literal text", "{INPUT}"),
+        ("neither sentinel here, just literal text", "{OUTPUT}"),
+    ],
+)
+def test_missing_placeholder_in_chat_template_raises(template, expected_in_message):
+    with pytest.raises(RuntimeError) as exc_info:
+        construct_chat_template(
+            tokenizer = _FakeTokenizer(),
+            chat_template = template,
+            extra_eos_tokens = ["</s>"],
+        )
+    assert expected_in_message in str(exc_info.value)
+
+
+def test_single_pair_template_raises_clear_error_not_attribute_error():
+    """One {INPUT}/{OUTPUT} pair (rather than the required two) used to
+    crash with AttributeError on `found.group(1)` after the for-loop
+    broke without setting `found`. Must raise RuntimeError now."""
+    template = "user: {INPUT}\nassistant: {OUTPUT}\n"
+    with pytest.raises(RuntimeError):
+        construct_chat_template(
+            tokenizer = _FakeTokenizer(),
+            chat_template = template,
+            extra_eos_tokens = ["</s>"],
+        )
+
+
+def test_error_message_excerpt_is_bounded():
+    """Error messages must include a bounded excerpt of the offending
+    template, not dump arbitrarily large content into the traceback."""
+    huge = ("garbage " * 5000) + "{INPUT}"  # ~40 KB, missing {OUTPUT}
+    with pytest.raises(RuntimeError) as exc_info:
+        construct_chat_template(
+            tokenizer = _FakeTokenizer(),
+            chat_template = huge,
+            extra_eos_tokens = ["</s>"],
+        )
+    msg = str(exc_info.value)
+    # Excerpt is repr-quoted and capped; total message should stay well
+    # under the template length.
+    assert len(msg) < 1000
+    assert "{OUTPUT}" in msg