perf(block-impact): byte-exact block slice enables subtractive LOO

[aspala]

Was

Behebt die Wurzel des gescheiterten subtraktiven LOO-Pfads und macht separator_counts + vowel_density wieder subtraktiv (korrekt).

Wurzelproblem

Der LOO-Pfad baute file-minus-block aus normalisierten structural tokens — die kollabieren inter-token-Whitespace, runden Indent auf 2-Space-Units und mappen Non-ASCII auf Spaces. Der reconstructed string wich also vom Source ab, und jede subtraktive Metrik (baseline ⊖ block) gegen eine Original-File-Baseline driftete mit. Das war der latente separator_counts-Bug (0/50 matches), der durch Entfernen von analyze_loo/2 umgangen worden war.

Fix

slice_without_original/2 schneidet den Block aus den Original-Bytes via line+col des ersten/letzten Tokens. block_content ist damit der verbatim Source-Span, reconstructed das Original minus diesem Span. Schnitte fallen auf Token-Grenzen → counts subtrahieren exakt.

• Vertrag: analyze_loo/2 nimmt einen geteilten Block-FileContext (einmal pro Node gebaut) statt eines rohen Strings → subtraktive Metriken extrahieren identifiers/tokens über dieselbe Pipeline wie die Baseline.
• separator_counts + vowel_density wieder subtraktiv, jetzt korrekt: ~23ms / ~7ms pro Node → ~0,1ms. Verifiziert vom subtractive_loo-Goldfile-Guard gegen reale verschachtelte Sample-Blocks.
• Bewusst NICHT subtraktiv (re-analyze-Fallback): punctuation-densities, halstead n1/n2, ngram, line-basierte — set-basiert oder blockgrenz-kontextabhängig, subtrahieren nicht exakt.

Messung (1/10-Subset, --telemetry)

• analyze_file pro Node: 196ms → 180ms (~8% head-LOO)
• Report-Output byte-identisch außer Timestamp (kein Drift)
• 921 Tests grün, Credo strict clean, Dialyzer pass

Ehrlicher Scope

Der subtraktive Hebel ist physisch auf ~8% begrenzt — die großen Posten (ctx-build, punctuation, halstead, ngram) sind mathematisch nicht subtraktiv. Dieser PR ist der saubere, korrekte Anteil + das Fundament (slice_without_original, geteilter block_ctx) für spätere Metriken (z.B. entropy via baseline-count-Cache). Der echte Laufzeit-Win kam aus #61 (base-snapshot).

[github-actions]

Score: C+ → C+ | Δ -1 pts | 0 blocks flagged across 8 files | 7 modified, 1 added

🟠 Code Health: C+ (63/100)

192 files · codeqa-action · 2026-06-07

Combined metric scores use cosine similarity: +1 = metric profile perfectly matches healthy pattern for this behavior, 0 = no signal, −1 = anti-pattern detected. Mapped to 0–100 using breakpoints (approx: ≥0.5→A, ≥0.2→B, ≥0.0→C, ≥−0.3→D, <−0.3→F); actual letter grades use the full 15-step scale.

Metric Changes

Category	Base	Head	Δ
Readability	88.26	97.81	+9.54
Complexity	30.54	41.25	+10.71
Duplication	0.57	0.59	+0.02
Structure	6.17	9.02	+2.85

%%{init: {'theme': 'neutral'}}%%
xychart-beta
    title "Code Health Scores"
    x-axis ["Readability", "Complexity", "Structure", "Duplication", "Naming", "Magic Numbers", "Combined Metrics"]
    y-axis "Score" 0 --> 100
    bar [94, 31, 88, 48, 96, 100, 65]

Loading

Readability       ███████████████████░   94  🟢 A
Complexity        ██████░░░░░░░░░░░░░░   31  🔴 D-
Structure         ██████████████████░░   88  🟢 A-
Duplication       ██████████░░░░░░░░░░   48  🟠 C-
Naming            ███████████████████░   96  🟢 A
Magic Numbers     ████████████████████  100  🟢 A
Combined Metrics  █████████████░░░░░░░   65  🔴 D

[github-actions]

🔍 Top Likely Issues (cosine similarity)

Most negative cosine = file's metric profile best matches this anti-pattern.

Behavior	Cosine	Score
dependencies.low_coupling	-0.56	-12.51
file_structure.single_responsibility	-0.52	-12.31
file_structure.line_count_under_300	-0.44	-9.39
code_smells.no_dead_code_after_return	-0.43	-33.98
scope_and_assignment.used_only_once	-0.42	-14.59
scope_and_assignment.shadowed_by_inner_scope	-0.34	-4.90
file_structure.line_length_under_120	-0.30	-8.31
scope_and_assignment.declared_close_to_use	-0.26	-1.51
code_smells.no_debug_print_statements	-0.24	-2.22
variable_naming.loop_var_is_single_letter	-0.23	3.55

🟢 Readability — A (94/100)

Codebase averages: flesch_adapted=97.81, fog_adapted=4.82, avg_tokens_per_line=9.52, avg_line_length=35.74

Metric	Value	Score
readability.flesch_adapted	97.81	100
readability.fog_adapted	4.82	100
readability.avg_tokens_per_line	9.52	72
readability.avg_line_length	35.74	100

🔴 Complexity — D- (31/100)

Codebase averages: difficulty=41.25, effort=234200.38, volume=4045.56, estimated_bugs=1.35

Metric	Value	Score
halstead.difficulty	41.25	42
halstead.effort	234200.38	0
halstead.volume	4045.56	46
halstead.estimated_bugs	1.35	47

🟢 Structure — A- (88/100)

Codebase averages: branching_density=0.14, mean_depth=3.86, avg_function_lines=8.30, max_depth=9.21, max_function_lines=19.95, variance=6.85, avg_param_count=1.16, max_param_count=2.05

Metric	Value	Score
branching.branching_density	0.14	76
indentation.mean_depth	3.86	88
function_metrics.avg_function_lines	8.30	89
indentation.max_depth	9.21	87
function_metrics.max_function_lines	19.95	100
indentation.variance	6.85	100
function_metrics.avg_param_count	1.16	100
function_metrics.max_param_count	2.05	100

🟠 Duplication — C- (48/100)

Codebase averages: redundancy=0.59, bigram_repetition_rate=0.54, trigram_repetition_rate=0.37

Metric	Value	Score
compression.redundancy	0.59	58
ngram.bigram_repetition_rate	0.54	38
ngram.trigram_repetition_rate	0.37	40

🟢 Naming — A (96/100)

Codebase averages: entropy=0.89, mean=6.65, variance=18.82, avg_sub_words_per_id=1.17

Metric	Value	Score
casing_entropy.entropy	0.89	100
identifier_length_variance.mean	6.65	100
identifier_length_variance.variance	18.82	85
readability.avg_sub_words_per_id	1.17	100

🟢 Magic Numbers — A (100/100)

Codebase averages: density=0.00

Metric	Value	Score
magic_number_density.density	0.00	100

🔴 Combined Metrics — D (65/100)

Category	Score	Grade
Code Smells	25	🔴 D-
Consistency	81	🟡 B+
Dependencies	19	🔴 E+
Documentation	83	🟡 B+
Error Handling	92	🟢 A-
File Structure	48	🟠 C-
Function Design	81	🟡 B+
Naming Conventions	90	🟢 A-
Scope And Assignment	28	🔴 D-
Testing	83	🟡 B+
Type And Value	89	🟢 A-
Variable Naming	74	🟡 B

🔴 Code Smells — D- (25/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
no_dead_code_after_return	-0.43	25	D-

🟡 Consistency — B+ (81/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
consistent_function_style	0.37	81	B+

🔴 Dependencies — E+ (19/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
low_coupling	-0.56	19	E+

🟡 Documentation — B+ (83/100)

Cosine similarity scores for 3 behaviors.

Behavior	Cosine	Score	Grade
file_has_module_docstring	0.30	77	B
function_has_docstring	0.45	86	A-
docstring_is_nonempty	0.45	87	A-

🟢 Error Handling — A- (92/100)

Cosine similarity scores for 3 behaviors.

Behavior	Cosine	Score	Grade
error_message_is_descriptive	0.52	90	A-
does_not_swallow_errors	0.60	92	A-
returns_typed_error	0.69	94	A

🟠 File Structure — C- (48/100)

Cosine similarity scores for 5 behaviors.

Behavior	Cosine	Score	Grade
single_responsibility	-0.52	21	E+
line_count_under_300	-0.44	24	E+
line_length_under_120	-0.30	30	D-
has_consistent_indentation	0.26	74	B
no_magic_numbers	0.57	91	A-

🟡 Function Design — B+ (81/100)

Cosine similarity scores for 3 behaviors.

Behavior	Cosine	Score	Grade
is_less_than_20_lines	0.33	79	B+
no_magic_numbers	0.38	82	B+
has_verb_in_name	0.40	83	B+

🟢 Naming Conventions — A- (90/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
function_name_is_not_single_word	0.50	90	A-

🔴 Scope And Assignment — D- (28/100)

Cosine similarity scores for 3 behaviors.

Behavior	Cosine	Score	Grade
used_only_once	-0.42	25	D-
shadowed_by_inner_scope	-0.34	28	D-
declared_close_to_use	-0.26	32	D-

🟡 Testing — B+ (83/100)

Cosine similarity scores for 2 behaviors.

Behavior	Cosine	Score	Grade
test_single_concept	0.27	74	B
test_name_describes_behavior	0.53	91	A-

🟢 Type And Value — A- (89/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
hardcoded_url_or_path	0.49	89	A-

🟡 Variable Naming — B (74/100)

Cosine similarity scores for 1 behaviors.

Behavior	Cosine	Score	Grade
name_is_generic	0.26	74	B

[github-actions]

---

kind: refactoring-tasks
path: /home/runner/work/codeqa-action/codeqa-action
timestamp: 2026-06-07T11:46:02.458052Z
overall_grade: C+
overall_score: 63
task_count: 0
critical: 0
high: 0
instructions: >-
Address the tasks below in order of severity (critical first).
After each fix, run the project's test suite and confirm it passes
before moving on.

No critical or high-severity blocks need attention. ✅