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+# Requirements: NetSynth
+
+**Defined:** 2026-03-26
+**Core Value:** Network traffic patterns are instantly recognizable as distinct sounds — a ping sounds different from HTTPS noise, which sounds different from a port scan.
+
+## v1.1 Requirements
+
+Requirements for custom sound mappings milestone. Each maps to roadmap phases.
+
+### Config Loading
+
+- [ ] **CFG-01**: User can create a TOML config file that overrides default sound mappings
+- [ ] **CFG-02**: Tool auto-discovers config from `./netsynth.toml` or `~/.config/netsynth/config.toml` (silent if absent)
+- [ ] **CFG-03**: User can specify an explicit config path via `--config` flag (error if file missing)
+- [ ] **CFG-04**: User can override individual values without replicating the entire default config (partial override)
+- [ ] **CFG-05**: Unknown keys in config file produce a clear error with the typo'd key name
+- [ ] **CFG-06**: User can run `netsynth --print-config` to see the effective config as commented TOML
+
+### Waveforms
+
+- [ ] **WAVE-01**: User can set waveform type per traffic class (sine, square, sawtooth, triangle)
+- [ ] **WAVE-02**: Non-sine waveforms use bandlimited additive synthesis (no aliasing artifacts)
+
+### Custom Rules
+
+- [ ] **RULE-01**: User can define custom classification rules in TOML (match by port and/or protocol, assign class name and sound)
+- [ ] **RULE-02**: User-defined rules take priority over built-in rules (prepend before defaults)
+- [ ] **RULE-03**: User-defined class names automatically get a synthesis layer (no silent gaps)
+
+## Future Requirements
+
+Deferred to later releases.
+
+### Audio Tuning
+
+- **TUNE-01**: User can configure time window duration via `--window` flag
+- **TUNE-02**: User can configure output duration when reading pcap files via `--duration` flag
+
+### Distribution
+
+- **DIST-01**: Single static binary with no runtime dependencies
+
+## Out of Scope
+
+| Feature | Reason |
+|---------|--------|
+| Stereo position configuration | Keeps v1.1 scope focused; add in future if requested |
+| Real-time audio playback | File output only — established v1.0 constraint |
+| GUI config editor | CLI-only tool; TOML is human-editable |
+| JSON/YAML config format | TOML chosen for readability; one format keeps it simple |
+| Config hot-reload | Non-interactive tool; config read once at startup |
+
+## Traceability
+
+Which phases cover which requirements. Updated during roadmap creation.
+
+| Requirement | Phase | Status |
+|-------------|-------|--------|
+| CFG-01 | - | Pending |
+| CFG-02 | - | Pending |
+| CFG-03 | - | Pending |
+| CFG-04 | - | Pending |
+| CFG-05 | - | Pending |
+| CFG-06 | - | Pending |
+| WAVE-01 | - | Pending |
+| WAVE-02 | - | Pending |
+| RULE-01 | - | Pending |
+| RULE-02 | - | Pending |
+| RULE-03 | - | Pending |
+
+**Coverage:**
+- v1.1 requirements: 11 total
+- Mapped to phases: 0
+- Unmapped: 11
+
+---
+*Requirements defined: 2026-03-26*
+*Last updated: 2026-03-26 after initial definition*