yoloyolo/.planning/phases/01-capture-and-classification/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-capture-and-classification	04	cli	go cobra signal-handling channels pipeline cli stderr-output	phase provides 01-capture-and-classification capture.StartCapture, capture.ListInterfaces, capture.OpenCapture from capture/capture.go (Plan 02) phase provides 01-capture-and-classification classify.Classifier, classify.DefaultRules, classify.ClassifiedPacket types from classify/ (Plan 01) phase provides 01-capture-and-classification aggregate.Aggregate, aggregate.PrintSummary, aggregate.PrintWindowLine, aggregate.AccumulateTotals from aggregate/ (Plan 03)	Cobra CLI binary (cmd/netsynth/main.go) wiring all three pipeline stages -i / --interface flag for specifying capture interface --list-interfaces flag that enumerates available interfaces and exits --verbose flag enabling per-window protocol activity on stderr Ctrl+C / SIGTERM clean shutdown with Aggregate done-channel propagation Exit summary showing per-protocol packet counts and percentages	02-audio-synthesis	added patterns github.com/spf13/cobra v1.10.2 (Cobra CLI framework) Cobra RunE pattern: RunE returns error, Cobra handles exit code signal.NotifyContext for clean SIGINT/SIGTERM shutdown — cancels context which closes packet channel which drains pipeline Three-stage pipeline via goroutine + channels: capture -> classify -> aggregate Atomic drop counter (droppedPtr) surfaced at exit if non-zero	created modified cmd/netsynth/main.go cmd/netsynth/main_test.go	Cobra RunE (not Run) used so errors propagate cleanly to stderr and exit code 1 signal.NotifyContext chosen over manual signal.Notify channel — cancels context automatically on SIGINT/SIGTERM, simpler shutdown chain classified channel buffered at 1024 to absorb burst traffic between capture and aggregate goroutines Permission error message lives in capture.StartCapture (Plan 02); main.go just returns it — single source of truth for platform-specific sudo hint	Pattern: context cancellation is the single stop signal — capture reads ctx.Done(), packet channel close propagates to classify goroutine, which closes classified channel, which drains Aggregate Pattern: pipeline stages communicate only via channels — no shared state beyond atomic drop counter	CAPT-01 CAPT-02 CAPT-04 CLAS-01 CLAS-03 CLAS-04	~15min	2026-03-25

Phase 01 Plan 04: CLI Integration Summary

Cobra CLI wiring all three pipeline stages (capture -> classify -> aggregate) with signal-handling, --verbose per-window stderr output, and Ctrl+C exit summary — completes Phase 1 runnable netsynth binary

Performance

• Duration: ~15 min
• Started: 2026-03-25T11:25:00Z
• Completed: 2026-03-25T11:40:00Z
• Tasks: 2 (1 code + 1 human-verify checkpoint)
• Files modified: 2

Accomplishments

• cmd/netsynth/main.go wires capture, classify, and aggregate packages into a three-stage goroutine pipeline with buffered channels
• Cobra CLI exposes -i/--interface, --list-interfaces, and --verbose flags with correct validation and error messages
• signal.NotifyContext propagates SIGINT/SIGTERM through context cancellation to cleanly drain all pipeline stages before exit
• Per-window verbose output enabled via onSnapshot callback into aggregate.PrintWindowLine on stderr
• Exit summary printed via aggregate.PrintSummary after pipeline drains — shows per-protocol packet counts with percentages
• Binary builds with CGO_ENABLED=0 (Phase 1 has no CGo dependency; LAME is deferred to Phase 2+)
• Manual smoke test approved: live capture, verbose output, and Ctrl+C summary all verified on real interface

Task Commits

Each task was committed atomically:

1. Task 1: Wire Cobra CLI with capture-classify-aggregate pipeline and signal handling - 1be56a5 (feat)
2. Task 2: Smoke test live capture on real interface - checkpoint:human-verify (approved by user, no code commit)

Plan metadata: TBD (docs: complete plan)

Files Created/Modified

• cmd/netsynth/main.go - Cobra root command, run() pipeline assembly, runListInterfaces(), signal handling
• cmd/netsynth/main_test.go - Tests: TestListInterfacesFlag, TestMissingInterfaceFlag, TestHelpOutput

Decisions Made

• Cobra RunE (not Run) pattern used so error propagates cleanly — Cobra prints to stderr and sets exit code 1
• signal.NotifyContext preferred over manual signal channel — context cancellation is already the pipeline stop signal, so one mechanism handles both
• classified channel buffered at 1024 to absorb classify goroutine burst processing without blocking packet capture
• Permission error message owned by capture.StartCapture, not main.go — keeps platform-specific hint in one place

Deviations from Plan

None — plan executed exactly as written. Task 1 implementation matched the plan's code template precisely. All acceptance criteria passed.

Issues Encountered

None — build succeeded on first attempt, tests passed, smoke test approved.

User Setup Required

Live capture requires elevated privileges. Two options:

1. Run as root: sudo ./netsynth -i eth0
2. Grant capability: sudo setcap cap_net_raw+eip ./netsynth then run without sudo

Next Phase Readiness

• Phase 1 complete: capture, classify, aggregate, and CLI all wired and verified
• Phase 2 (audio synthesis) receives WindowSnapshot channel from aggregate.Aggregate — the Phase 2 synthesizer plugs in between the Aggregate output and the final exit summary
• No blockers for Phase 2; frequency mapping and oscillator math are the next open design decisions

Self-Check: PASSED

• cmd/netsynth/main.go exists
• cmd/netsynth/main_test.go exists
• 01-04-SUMMARY.md exists
• Commit 1be56a5 (feat(01-04): wire Cobra CLI) confirmed in git history

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Phase: 01-capture-and-classification Completed: 2026-03-25