• There are 2,070 files with units, with 163,218 lines of code.
• 0 very complex files (McCabe index sum 251+; 0 lines of code)
• 1 complex files (McCabe index sum 126-250; 478 lines of code)
• 2 medium complex files (McCabe index sum 51-125; 473 lines of code)
• 7 slightly complex files (McCabe index sum 26-50; 1,668 lines of code)
• 2,060 simple files (McCabe index sum 1-25; 160,599 lines of code)
• 1,384 main files have no units (e.g. languages without unit analysis, or files without functions) and are not classified.

The McCabe index of a file grows with its size: per 100 lines tells a large but plain file from a dense one, and most complex unit whether the complexity sits in one unit or is spread over many.

File	# lines	# units	McCabe index (sum)	per 100 lines	most complex unit
refusal_fallback.rb in lib/anthropic/helpers	478	28	145	30	28
config_provider.rb in lib/anthropic/credentials	275	21	76	28	11
client.rb in lib/anthropic	198	7	56	28	33
base_model.rb in lib/anthropic/internal/type	285	14	41	14	12
credentials.rbi in rbi/anthropic	215	33	33	15	1
util.rb in lib/anthropic/internal	294	21	32	11	5
middleware.rb in lib/anthropic	168	14	31	18	5
pooled_net_requester.rb in lib/anthropic/internal/transport	168	7	31	18	9
base_client.rb in lib/anthropic/internal/transport	448	9	30	7	18
constants.rb in lib/anthropic/credentials	90	10	29	32	6
base_model.rbi in rbi/anthropic/internal/type	229	24	24	10	1
mcp.rb in lib/anthropic/helpers/tools	323	12	24	7	5
runner.rb in lib/anthropic/helpers/tools	349	10	22	6	7
credentials.rb in lib/anthropic	82	3	20	24	11
token_cache.rb in lib/anthropic/credentials	99	5	19	19	11
messages.rb in lib/anthropic/resources	118	7	18	15	5
converter.rb in lib/anthropic/internal/type	174	8	18	10	9
client.rb in lib/anthropic/helpers/google_cloud	118	2	18	15	17
config.rb in lib/anthropic/credentials	62	6	18	29	8
workload_identity.rb in lib/anthropic/credentials	122	8	18	15	5
middleware.rbi in rbi/anthropic	287	17	17	6	1
union.rb in lib/anthropic/internal/type	123	7	17	14	7
beta_spend_summary.rb in lib/anthropic/models/beta/organization	115	3	17	15	7
event_accumulator.rb in lib/anthropic/helpers/sessions	74	6	16	22	9
client.rb in lib/anthropic/helpers/bedrock	165	4	15	9	12
credentials_file.rb in lib/anthropic/credentials	71	7	15	21	8
util.rbi in rbi/anthropic/internal	117	14	14	12	1
messages.rb in lib/anthropic/helpers	174	3	14	8	7
hash_of.rb in lib/anthropic/internal/type	80	7	13	16	3
beta_web_fetch_url_sources.rb in lib/anthropic/models/beta	91	3	13	14	5
beta_managed_agents_error.rb in lib/anthropic/models/beta/memory_stores	71	1	13	18	13
raw_content_block_start_event.rb in lib/anthropic/models	70	1	13	19	13
content_block.rb in lib/anthropic/models	65	1	13	20	13
web_fetch_url_sources.rb in lib/anthropic/models	88	3	13	15	5
in_memory_config.rb in lib/anthropic/credentials	60	4	13	22	5
array_of.rb in lib/anthropic/internal/type	61	6	12	20	4
client.rb in lib/anthropic/helpers/vertex	139	3	12	9	10
beta_spend_summary.rbi in rbi/anthropic/models/beta/organization	374	11	11	3	1
batch_create_params.rbi in rbi/anthropic/models/beta/messages	799	11	11	1	1
beta_web_fetch_url_sources.rbi in rbi/anthropic/models/beta	352	11	11	3	1
web_fetch_url_sources.rbi in rbi/anthropic/models	324	11	11	3	1
beta_dreaming_error.rb in lib/anthropic/models/beta	60	1	11	18	11
identity_token_file.rb in lib/anthropic/credentials	38	3	11	29	5
beta_plugin.rbi in rbi/anthropic/models/beta/organization	410	10	10	2	1
errors.rb in lib/anthropic	141	6	10	7	3
token_page.rb in lib/anthropic/internal	47	5	10	21	3
page.rb in lib/anthropic/internal	50	5	10	20	3
beta_error.rb in lib/anthropic/models	53	1	10	19	10
error_object.rb in lib/anthropic/models	53	1	10	19	10
base_tool.rb in lib/anthropic/helpers/tools	57	6	10	18	4

• File complexity is the sum of the McCabe indexes (conditional complexity) of the units (methods, functions...) in a file.
• Files are classified in five categories based on that sum: 1-25 (simple files), 26-50 (slightly complex files), 51-125 (medium complex files), 126-250 (complex files), 251+ (very complex files). The default bands are five times the unit complexity bands, as a file is a group of units.
• Only main code files with units are classified. Files without units (languages without unit analysis, or files without functions) have no complexity to measure and are left out rather than counted as simple.
• A very complex file holds many decisions, which often means it has too many responsibilities: a candidate to split, and a place where changes need more testing.