keyhunter/.planning/phases/01-foundation/01-04-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
01-foundation	04	engine	scanning aho-corasick entropy regex ants goroutine-pool pipeline	phase provides 01-foundation-02 Provider Registry with AC() automaton and List() for pattern matching	Three-stage scanning pipeline: AC pre-filter, regex+entropy detector, results channel Engine.Scan(ctx, source, config) -> <-chan Finding Source interface for input adapters FileSource for single-file scanning Shannon entropy function pkg/types.Chunk shared type breaking circular imports	cli-scan input-sources verification output-formats	added patterns ants/v2 pkg/types three-stage-channel-pipeline goroutine-pool-with-waitgroup overlapping-chunk-reads	created modified pkg/types/chunk.go pkg/engine/finding.go pkg/engine/entropy.go pkg/engine/filter.go pkg/engine/detector.go pkg/engine/sources/source.go pkg/engine/sources/file.go pkg/engine/engine.go pkg/engine/scanner_test.go testdata/samples/anthropic_key.txt testdata/samples/multiple_keys.txt	pkg/types/chunk.go breaks engine<->sources circular import ants pool with sync.WaitGroup+Mutex for detector stage coordination FileSource uses os.ReadFile with 256-byte chunk overlap; mmap deferred to Phase 4 Pool.Release() used instead of ReleaseWithTimeout (not in ants/v2 API)	Three-stage channel pipeline: Source->KeywordFilter->Detect->resultsChan Shared types in pkg/types to avoid circular imports between engine and sources Overlapping chunks (256 bytes) to prevent key splitting at boundaries	CORE-01 CORE-04 CORE-05 CORE-06	5min	2026-04-05

Phase 1 Plan 4: Scan Engine Summary

Three-stage scanning pipeline with Aho-Corasick pre-filter, regex+entropy detection via ants goroutine pool, and FileSource adapter

Performance

• Duration: 5 min
• Started: 2026-04-05T09:16:37Z
• Completed: 2026-04-05T09:21:30Z
• Tasks: 2
• Files modified: 12

Accomplishments

• Three-stage pipeline (AC keyword filter -> regex+entropy detector -> results channel) working end-to-end
• Shannon entropy function correctly discriminates real keys (>= 3.5 bits/char) from low-entropy strings
• ants v2 goroutine pool with configurable worker count for parallel detection
• FileSource with overlapping chunk reads preventing key splitting at boundaries
• All 12 engine tests pass including pipeline integration tests against real testdata

Task Commits

Each task was committed atomically:

1. Task 1: Shared types, Finding, Shannon entropy - 45cc676 (feat)
2. Task 2: Pipeline stages, engine, FileSource, tests - cea2e37 (feat)

Plan metadata: (pending final commit)

Note: TDD tasks had RED-GREEN commits merged into single task commits

Files Created/Modified

• pkg/types/chunk.go - Shared Chunk struct (Data, Source, Offset) breaking circular import
• pkg/engine/finding.go - Finding struct with MaskKey for masked key output
• pkg/engine/entropy.go - Shannon entropy using math.Log2 (~15 lines)
• pkg/engine/filter.go - KeywordFilter using Aho-Corasick automaton
• pkg/engine/detector.go - Detect applying regex patterns + entropy threshold
• pkg/engine/engine.go - Engine.Scan orchestrating 3-stage pipeline with ants pool
• pkg/engine/sources/source.go - Source interface using pkg/types.Chunk
• pkg/engine/sources/file.go - FileSource with overlapping chunk reads
• pkg/engine/scanner_test.go - 7 integration tests replacing stub tests
• pkg/engine/entropy_test.go - 6 unit tests for Shannon and MaskKey
• testdata/samples/anthropic_key.txt - Fixed key length for regex match
• testdata/samples/multiple_keys.txt - Fixed anthropic key length

Decisions Made

• Used pkg/types/chunk.go to break the engine<->sources circular import (Go requires this pattern)
• ants Pool.Release() instead of ReleaseWithTimeout (method doesn't exist in current ants/v2 API)
• FileSource reads entire file via os.ReadFile then splits into overlapping chunks -- mmap deferred to Phase 4
• Mutex protects resultsChan writes from detector goroutines to prevent channel deadlock

Deviations from Plan

Auto-fixed Issues

1. [Rule 1 - Bug] Fixed Anthropic test key lengths too short for regex pattern

• Found during: Task 2 (pipeline integration tests)
• Issue: anthropic_key.txt and multiple_keys.txt had Anthropic keys with suffix < 93 chars, failing the sk-ant-api03-[A-Za-z0-9_\-]{93,} regex
• Fix: Extended synthetic key suffixes to 101 and 102 chars respectively
• Files modified: testdata/samples/anthropic_key.txt, testdata/samples/multiple_keys.txt
• Verification: Regex matches confirmed, all pipeline tests pass
• Committed in: cea2e37 (Task 2 commit)

2. [Rule 1 - Bug] Fixed ants API: ReleaseWithTimeout does not exist

• Found during: Task 2 (compilation)
• Issue: Plan specified pool.ReleaseWithTimeout(5*time.Second) but ants/v2 only has pool.Release()
• Fix: Changed to pool.Release() and removed unused time import
• Files modified: pkg/engine/engine.go
• Verification: Build succeeds, all tests pass
• Committed in: cea2e37 (Task 2 commit)

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Total deviations: 2 auto-fixed (2 bugs) Impact on plan: Both fixes necessary for correctness. No scope creep.

Issues Encountered

None beyond the auto-fixed deviations above.

User Setup Required

None - no external service configuration required.

Next Phase Readiness

• Scan engine ready for CLI integration (Plan 05: keyhunter scan)
• Engine.Scan() returns <-chan Finding ready for any consumer (CLI, web, bot)
• Source interface ready for additional adapters (dir, git, stdin) in Phase 4

Self-Check: PASSED

All 10 created files verified on disk. Both task commits (45cc676, cea2e37) verified in git log.

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Phase: 01-foundation Completed: 2026-04-05