refactor: rationalise channel data model field types and vendor mappings

[pskillen]

Problem

The internal Channel model was bootstrapped from OpenGD77 CPS columns and most optional fields are untyped strings in the UI and model. The channel edit form exposes free-text inputs for values that are really numbers or enums, often carrying OpenGD77-specific wire values that are opaque in a vendor-neutral tool.

Examples today:

Field	Stored / UI today	Desired internal semantics (illustrative)
power	P2, Master (OpenGD77)	50% / 100% or low / high / full
bandwidthKHz	"12.5" string	12.5 number or enum narrow / wide
colourCode	string	1–15 integer
timeslot	string	1 | 2 enum
squelch	75%, Disabled	typed enum or numeric level
rxOnly	Yes / No string	boolean
transmitTimeout	string seconds	number
rxTone / txTone	free text	structured CTCSS/DCS/none

This makes validation weak, UI inconsistent, and export mappers pass vendor strings through unchanged rather than translating at the boundary.

Intended outcome

Manually rationalise each channel field — decide the vendor-neutral internal representation, document it, then update code and ETL.

Per-field deliverables

For each Channel field (and related entities as discovered):

1. Decision — internal type, allowed values, default, whether vendor-specific values live only in import/export mappers.
2. Documentation — update docs/features/data-model/README.md with typed definitions and semantics.
3. Reference doc — where values are domain knowledge (power levels, tones, bandwidths), add or extend docs/reference/ entries.
4. Model — update src/models/codeplug.ts types and channelFieldDefaults().
5. Migration — schema version bump; migrate existing localStorage projects (map old string values → new types).
6. Import — OpenGD77 (src/lib/import/opengd77/) maps vendor wire → internal model.
7. Export — OpenGD77 (src/lib/export/opengd77/) maps internal model → vendor wire.
8. UI — channel edit/detail/list use appropriate controls (Select, NumberInput, Checkbox, not TextInput) per field.
9. Import/export docs — update docs/features/import/opengd77.md and export docs with mapping tables.

Suggested field groups (non-exhaustive)

• RF: bandwidthKHz, power, rxTone, txTone, squelch, rxOnly
• DMR: colourCode, timeslot, dmrId
• Behaviour: transmitTimeout, voxEnabled, scanSkip (some already boolean)
• Frequencies: consider numeric MHz internally vs string (separate decision)

Power is the canonical motivating example: internal powerLevel: 'low' | 'high' | 'full' (or %) with OpenGD77 export mapping low → P2, full → Master, etc.

Affected

• src/models/codeplug.ts + migration
• src/lib/import/opengd77/, src/lib/export/opengd77/
• src/routes/channels/ (edit, detail, list)
• src/lib/validation/ (if present) — typed validation rules
• docs/features/data-model/, docs/features/import/opengd77.md, docs/features/export/
• docs/reference/ — new field-value references as needed

Notes / dependencies

• Large, multi-commit refactor — likely one PR with atomic commits per field or field group.
• Pairs with refactor: change analog/digital field to a more generic mode field #45 (mode enum) and feat: show mode-appropriate fields on channel detail and edit pages #48 (mode-appropriate field visibility) — coordinate so enums align with mode applicability.
• Vendor strings that have no neutral equivalent may remain in vendorExtras until a vendor adapter needs them.
• DM32 / qDMR mappings can be stubbed or deferred if export adapters are not yet shipped.

Out of scope

• Automatic inference of field types from CSV headers without explicit design decisions.
• Changing entity relationships (contacts, TG lists) — channel scalar fields only unless unavoidable.

Workflow note

Branch from origin/main, atomic conventional commits per field/group, PR linking Closes #. Use progress-tracking / feature-docs skills for a rationalisation checklist.

[pskillen]

Tracked under epic #93 (pristine vendor-neutral internal data model). This is Phase 2 of that epic.

[pskillen]

Phase 2 execution subplan ready (assumes Phase 1 / PR #96 merged to main).

Plan: .cursor/plans/phase2_typed_channel_fields_52.plan.md

Branch: 52/paddy/typed-channel-fields

Slices (12): shared test builders → schema v5 scaffold → per-field typing (rxOnly, Hz frequencies, bandwidth, power, squelch, tones, DMR fields, TOT) → docs + doc-audit #3 → PR Closes #52.

Schema: v4 → v5 with v4→v5 migration fixture.

Epic handoff docs: docs/features/data-model/pristine-model-refactor-progress.md.