Add note_velocity and pitch_bend mapping types; don't resend unchanged CCs

[cpmpercussion]

Implements the design in #98.

["note_velocity", channel]

• Input: a note-on sets the note_on dimensions on its channel to note/127 and the note_velocity dimensions on its channel to velocity/127, as one update (one model input, one log row). Velocity-0 note-ons are still note-offs and change nothing.
• Output: sends nothing by itself. Every note dimension on the channel takes its velocity from the first note_velocity dimension there, as max(1, round(v * 127)), so it never sends a velocity-0 note-off. Polyphonic note dimensions on a channel share it.

["note_on", channel, velocity]: a fixed output velocity, clamped to 1–127. A note_velocity dimension on the same channel overrides it. On input it behaves like ["note_on", channel]. Without the third element, velocity stays at 127.

["pitch_bend", channel]: the value is raw / 16383 for the 14-bit value raw (0–16383, centred at 8192) on input, and round(v * 16383) on output. This matches what impsy-auv3 and impsy-web already do. Over WebSocket it's /channel/{ch}/pitchbend/{raw}.

Don't resend unchanged CC and pitch bend values (#110). Each output step used to send every CC and pitch bend. Now a CC or pitch bend is skipped when it's the same MIDI value as the last one sent to that channel (and controller). Notes are always sent. The remembered values are cleared on disconnect and when a new WebSocket client connects, so the next step sends everything. This rule has no time window, so it's deterministic and the vectors can describe it. impsy-auv3 instead dedups per dimension within a configurable time window, and should be brought into line with this.

Other changes:

• The web UI realtime labels show Vel chN and PB chN.
• docs/config.md documents the new types and the WebSocket message.
• Unit tests, and new conformance cases in midi_input, midi_output, websocket_input, websocket_output and pipeline. SPEC_VERSION goes to 1.0.0, because dedup changes two existing cases: note_and_cc_encoding and websocket_output no longer repeat a CC whose value didn't change. There's also a new unchanged_cc_and_pitch_bend_not_resent case.

Follow-ups in the other repos: impsy-auv3 and impsy-web need a "Note velocity" type, the fixed-velocity form, the dedup rule, and to pass the new vectors. impsy-auv3's config parser currently returns nil for unknown types; see the comment on #98.

Refs #98
Fixes #110

🤖 Generated with Claude Code

https://claude.ai/code/session_016oUxTsghWZWfnCnnkKcuNv

[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved review issues were identified.

Review effort: Lite
Findings: None

What changed in this PR

Adds MIDI note_velocity, fixed-velocity note, and pitch_bend mapping support across runtime handling, WebSocket transport, UI labels, documentation, tests, and conformance vectors.

Changes:

• Adds velocity-aware MIDI note and pitch-bend input/output handling.
• Adds WebSocket support and realtime labels.
• Updates documentation, tests, and specification vectors.

File	Reviewed changes
tests/​test_webui.py	Realtime label tests
tests/​test_utils.py	Mapping behavior tests
tests/​test_impsio.py	WebSocket tests
spec/​vectors/​websocket_output.json	WebSocket output vectors
spec/​vectors/​websocket_input.json	WebSocket input vectors
spec/​vectors/​playback.json	Specification version updates
spec/​vectors/​pipeline.json	Pipeline conformance vectors
spec/​vectors/​model.json	Specification version updates
spec/​vectors/​midi_output.json	MIDI output vectors
spec/​vectors/​midi_input.json	MIDI input vectors
spec/​vectors/​dataset.json	Specification version updates
impsy/​web_interface.py	Realtime labels
impsy/​utils.py	MIDI mapping and conversion logic
impsy/​impsio.py	WebSocket pitch-bend transport
impsy/​conformance.py	Conformance cases and version
docs/​config.md	Mapping and WebSocket documentation

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