[agent] Hardware-testing fixes for the Swift client

[drycode]

Four defects found by running #12 on real hardware — Studio, real dictation, against the existing Python server. It now works end to end. Every one of these passed both test suites, because they test what the code says and these are failures of what it reaches.

The hotkey misses almost every release

Hotkey.swift reconstructed the chord from keycode + modifier flags and applied that test to both edges. The flags describe the instant the event was generated, and releasing Ctrl+Alt+Space almost always lifts a modifier at or before the space bar — so the space key-UP arrives with the modifier bits already clear.

Measured with a bare session tap over 45 s of ordinary use:

DOWN events: 303      (auto-repeat while held)
UP events:     1
tap disabled:  0      (not the timeout path)

In the agent that left a capture that never ended, and since beginCapture() guards on state == .idle, every later press was ignored — presenting as "the hotkey stopped working".

This is the Phase 0 spike the design asked for, and it now has an answer. Switched to Carbon RegisterEventHotKey: pressed and released arrive as distinct events, the release is not conditional on modifier state, it consumes the chord so it does not also reach the focused app, and it needs no permission of its own — so no Input Monitoring grant is required. Accessibility is still needed for the ⌘V, so it is one grant either way.

The client could not reach any deployment

AgentController hardcoded http://127.0.0.1:<harkPort>/dictate with the key from ~/.config/hark/key — the server's deployment config used as the client's. That breaks the two-machine setup, and it also breaks a single machine whose server binds a tailnet address: measured here, 127.0.0.1:8911 refuses while 100.64.66.46:8911 answers 200.

Adds ClientConfig (~/.config/hark/client.json) and enforces the transport policy the design already specifies rather than assuming it — plain HTTP to loopback always; to a numeric IP only with an explicit allowPlaintext, because a tailnet is a defensible place for plaintext but it should be a stated decision; to a hostname never, since a MagicDNS name is a hostname. Absent config falls back to the previous behaviour.

Recorder accumulated across captures

samples and peak are instance properties on a long-lived Recorder, and neither start() nor stop() cleared them. Capture 2 transcribed 1+2, capture 3 transcribed 1+2+3, and the WAV grew without bound. Presented as the transcript repeating the previous dictation.

There was no presentation layer

private func alert(_ message: String) {
    log.info(message)
    NSWorkspace.shared.notificationCenter.post(name: .init("HarkAlert"), object: message)
}                                    // nothing observes "HarkAlert"

private func brief(_ message: String) { _ = message }

The whole diagnostic surface — 401, 415, 400, 503, transport failure, "heard nothing", "paste withheld (focus moved)" — was discarded. Added Overlay, a non-activating floating panel so it never pulls focus from what you are dictating into, and wired all three paths to it. The menu bar item stays.

Smaller

• 200 ms ⌘V hold. Posting key-up immediately after key-down is a zero-duration keystroke that some apps drop. hs.eventtap.keyStroke holds 200 ms (local keyDelay = 200000); same tap, same flags, the gap was the only difference.
• AXIsProcessTrusted re-checked at paste time, and on failure the user is told the transcript is on the clipboard. Everything before that point reports success either way, so an untrusted process was indistinguishable from a dropped event.
• requestAccess waits for its answer instead of discarding it. An ungranted process is not refused the device — it receives full-length buffers of zeros.
• status.json no longer reports a constant. hotkey was a hardcoded "registered" regardless of whether anything was bound, which is why the dead tap looked healthy from outside.
• Trailing space on the transcript, so consecutive dictations do not run together. Client-side deliberately: the server should return the transcript, not presentation whitespace.
• HARK_CLIENT_CONFIG overrides the config path, mirroring the server's HARK_CONFIG. Neither homeDirectoryForCurrentUser nor NSHomeDirectory() honours $HOME on macOS, so HOME=... hark agent silently reads the real config — which produced a round of "passing" policy checks all reading the same live file.

Verification

Studio: recording, transcription and paste all working; repeats gone; indicator visible; consecutive dictations separated. The 48 SwiftPM tests pass at every commit.

Not covered here, and still open: wiring install-client.sh onto hark agent, deleting the Lua client, and whether hark serve replaces the Python server — nothing here tested the server rewrite.