style(anthropic): trim excess thinking-block predicate/test commentary

litellm/litellm_core_utils/prompt_templates/factory.py

@@ -2302,20 +2302,14 @@ def sanitize_messages_for_tool_calling(
 def _is_unsignable_thinking_block(block: object) -> bool:
     """A thinking block that Anthropic cannot accept on input.
 
-    Anthropic verifies the thinking signature cryptographically, so a block whose
-    signature is null, empty, or missing (e.g. from an open-source reasoning model)
-    is rejected with a 400 and must be dropped rather than blanked or repaired, and
-    so is a block whose signature or data carries another provider's encrypted
-    reasoning. A `redacted_thinking` block Anthropic minted is always kept.
-
-    Anthropic also rejects a `thinking` block whose `thinking` text is empty or
-    whitespace-only ("each thinking block must contain thinking"), regardless of
-    signature. This shape reaches us when a caller replays a `thinking_blocks`
-    history item that originated from a non-Anthropic reasoning provider (e.g. an
-    OpenAI Responses-API turn with no summary text) through this Anthropic-shaped
-    request path (`/v1/chat/completions` -> anthropic/vertex_ai's claude models),
-    which is the same failure the Anthropic Responses-bridge adapter guards
-    against (see PR #36033) for its own separate content-block path.
+    Anthropic verifies the signature cryptographically, so a block with a null,
+    empty, or missing signature (e.g. from an open-source reasoning model) is
+    rejected with a 400, and so is a block whose signature or data carries
+    another provider's encrypted reasoning. It also rejects a `thinking` block
+    whose text is empty or whitespace-only ("each thinking block must contain
+    thinking"), regardless of signature, e.g. when a `thinking_blocks` history
+    item from a non-Anthropic reasoning provider is replayed through this path.
+    `redacted_thinking` blocks carry no signature and are always kept.
     """
     if is_encrypted_reasoning_block(block):
         return True

tests/test_litellm/litellm_core_utils/prompt_templates/test_litellm_core_utils_prompt_templates_factory.py

@@ -3722,14 +3722,7 @@ def test_convert_to_anthropic_tool_invoke_keeps_paired_server_tool_use():
         server_result,
     ]
 def test_anthropic_messages_pt_drops_empty_but_signed_thinking_block():
-    """
-    Anthropic rejects a `thinking` block whose `thinking` text is empty, even
-    when it carries a valid-looking signature, with:
-        400 messages.N.content.M.thinking: each thinking block must contain thinking
-    This shape is reachable via cross-provider replay of a `thinking_blocks`
-    history item (see PR #36033), so `_is_unsignable_thinking_block()` must
-    also check the thinking text, not just the signature.
-    """
+    """An empty-but-signed thinking block must still be dropped."""
     from litellm.litellm_core_utils.prompt_templates.factory import (
         anthropic_messages_pt,
     )
@@ -3762,10 +3755,7 @@ def test_anthropic_messages_pt_drops_empty_but_signed_thinking_block():
 
 
 def test_anthropic_messages_pt_keeps_non_empty_signed_thinking_block():
-    """
-    Regression: a real, non-empty, signed thinking block must still pass
-    through unchanged.
-    """
+    """Regression: a non-empty, signed thinking block passes through unchanged."""
     from litellm.litellm_core_utils.prompt_templates.factory import (
         anthropic_messages_pt,
     )
@@ -3800,11 +3790,7 @@ def test_anthropic_messages_pt_keeps_non_empty_signed_thinking_block():
 
 
 def test_anthropic_messages_pt_keeps_redacted_thinking_block():
-    """
-    Regression: `redacted_thinking` blocks carry no signature and no plaintext
-    `thinking` field by design, and must always be kept regardless of the new
-    emptiness check (which only applies to `type == "thinking"` blocks).
-    """
+    """Regression: redacted_thinking blocks are unaffected by the emptiness check."""
     from litellm.litellm_core_utils.prompt_templates.factory import (
         anthropic_messages_pt,
     )
@@ -3836,11 +3822,7 @@ def test_anthropic_messages_pt_keeps_redacted_thinking_block():
 
 
 def test_anthropic_messages_pt_drops_unsigned_thinking_block():
-    """
-    Regression (pre-existing behaviour): a thinking block with no signature
-    (or an empty/null one) must still be dropped, independent of whether the
-    thinking text is populated.
-    """
+    """Regression: an unsigned thinking block is still dropped, regardless of text."""
     from litellm.litellm_core_utils.prompt_templates.factory import (
         anthropic_messages_pt,
     )
@@ -3873,24 +3855,7 @@ def test_anthropic_messages_pt_drops_unsigned_thinking_block():
 
 
 def test_is_unsignable_thinking_block_treats_whitespace_only_as_empty():
-    """
-    Edge case: a `thinking` field that is present but whitespace-only (e.g.
-    a single trailing newline forwarded from another provider's empty
-    reasoning summary) is functionally empty and Anthropic's API will still
-    reject it with "each thinking block must contain thinking". We treat it
-    the same as a fully empty string and drop the block.
-
-    Note the sibling check ~30 lines below this function's definition
-    (the "don't pass empty text blocks" comment) uses a bare
-    `len(thinking_block) > 0`, which by itself would treat whitespace-only
-    text as non-empty. That sibling check is always combined with
-    `not _is_unsignable_thinking_block(m)` in an `and`, so this function's
-    stricter whitespace-aware check is still the one that decides whether a
-    whitespace-only block survives — the two checks don't disagree in
-    practice, but this function is intentionally the stricter of the two
-    since it is also called standalone (via `_drop_unsignable_thinking_blocks`)
-    without that extra `len(...) > 0` guard.
-    """
+    """Whitespace-only `thinking` text is treated as empty and dropped."""
     from litellm.litellm_core_utils.prompt_templates.factory import (
         _is_unsignable_thinking_block,
     )