The scaler_per_tok variable on line 501 uses integer truncation division (num_kv_heads * dim / KV_QUANT_GROUP_SIZE) rather than the ceiling division used everywhere else (e.g., compact_to_windows at line 532: (dim + KV_QUANT_GROUP_SIZE - 1) / KV_QUANT_GROUP_SIZE). If dim is not a multiple of KV_QUANT_GROUP_SIZE (32), the scale buffer offsets will be computed incorrectly, causing data corruption when erasing scale entries. Use the same ceiling formula as compact_to_windows and the rest of the codebase.

The variable name scaler_per_tok is a misspelling; it should be scales_per_tok (consistent with scales_per_token used elsewhere in the same file, e.g., line 141 and line 533).

In test_complete_thinking_toggle, when cactus_init successfully loads the model but then fails, it returns false without printing a skip message (line 105: if (!model) return false;). However, in the analogous test test_prompt_thinking_injection at line 76, it returns true with a skip message. This inconsistency means a failure to load the model in test_complete_thinking_toggle will cause the test suite to report a failure rather than a skip, which is unexpected since the test is conditional on having a CACTUS_TEST_MODEL set.

The new <|tool_call> format is detected but the actual parsing logic at line 516 only handles content starting with "call:". If <|tool_call>...<tool_call|> content doesn't use the same call:function_name{...} format as <start_function_call>, then tool calls using this format will be silently swallowed — the tags are erased from the response (line 548) but no function call is extracted. At minimum this should be documented; if the format is different, the parsing branch needs to be added.

KVCache::init accesses layer_dims[i] for i in [0, num_layers) without verifying that layer_dims.size() >= num_layers. If a caller passes a vector shorter than num_layers, this results in undefined behavior. A defensive assert or bounds check should be added, e.g., assert(layer_dims.size() >= num_layers).

The test_complete_thinking_toggle test does not effectively verify that thinking is enabled or disabled. ok1 only checks that the completion succeeded ("success":true), not that a "thinking" field is present when thinking is enabled. ok2 checks that "thinking" is absent when disabled — but since cactus_complete.cpp never calls strip_thinking_block or passes thinking to construct_response_json, this check will always pass regardless of whether the feature works. The test needs to also verify resp1.find("\"thinking\"") != std::string::npos once the wiring is added.

The enable_thinking_if_supported option is parsed in parse_options_json and the prompt formatting functions accept it, but the main completion path (cactus_complete.cpp) never wires these together. Since cactus_complete.cpp is not modified in this PR, the new feature is silently broken:

1. parse_options_json is called without the &enable_thinking_if_supported pointer argument, so the parsed value is discarded.
2. format_chat_prompt is called without passing enable_thinking_if_supported, so it uses the default value of true regardless of what the caller requested.
3. strip_thinking_block is never called after generation, so the thinking field never appears in the response JSON.

The test_complete_thinking_toggle test will pass for the wrong reason: resp2.find("\"thinking\"") returns npos because thinking is never extracted, not because thinking was disabled. The wiring changes to cactus_complete.cpp are missing from this PR.