[wow-miley]

Closes #121 (PHO-65).

The gate (Task A)

Recon is in .context/issue-121-lumos-sequence.md locally; the decisions that make this a wire format, for approval:

1. One segment per step, named by the step. Socket's capture walk chains one-shots back to back (ready→thinking straight into thinking→idle) and loops a state only on its first visit; Dots' "loop step with an arriving transition" model cannot say that. Explicit steps round-trip the existing segment list 1:1.
2. A step naming what the orb already shows applies nothing, and sample reports no arrival for it. Loop steps rest where their one-shot landed. Glyphs always fire.
3. Step names are unique, because TraceStateMachine resolves by name.

Tasks B–E are built behind the gate so the format can be read against working code.

What's here

• :phosphor-lumos — LumosStep, LumosTransition, LumosSequence (fromJson/toJson, sealed LumosSequenceError, pure sample), LumosSequencePlayer (ticks while connected ∧ uncontrolled ∧ playing, dt capped at 0.1 s, control()/connect() return releases), LiveFrameSource.follow(player, clock), OrbStepper(…, player). Look is now @Serializable. kotlinx-serialization-json added to commonMain; lockfiles regenerated and unchanged.
• :phosphor-trace — SignalGenerator.play(sequence) / play(player) / stopSequence(), CaptureConfig.sequence + forSequence(…), LumosSequence.frameLayout(fps); the trace's paramSnapshot carries the sequence JSON. Validation: exclusive with cues/segments, fps >= 10, every step at least a frame, clip holds one pass.
• :phosphor-lumos-compose — LumosOrb(source, player, …) connects while running and releases when off screen or paused.
• :phosphor-lumos-cli — StateMachineDemo loads demo-sequence.json; runStateMachineDemo depends on jvmProcessResources.
• :phosphor-core — AtmosphereChoreographer.transitionSpec(from, to) made public; timeline {} KDoc points here.
• docs/LUMOS_SEQUENCE.md.

Proofs

• FormSeamByteIdentityTest: the T3 20-frame clip restated as a sequence encodes to the same SHA-256 (with the cue config's paramSnapshot put in place).
• StateMachineDemoSequenceTest: demo-sequence.json lays out to the old Beat frame table and captures to the same cell columns, ambient, glyphs and ticks as the cue script; every step name resolves through TraceStateMachine.
• SequenceCaptureTest: the live generator playing the sequence emits frame for frame what the capture recorded; two captures are byte-identical.

Deviations from the ticket, flagged

• No CHANGELOG.md — AGENTS.md forbids one. KDoc on CaptureConfig.cues, Oscilloscope, SignalGenerator and timeline {} carry the notes instead.
• demo-sequence.json is the demo's existing 13-step state-and-form script, not seven PROPEL looks. A look baked into a loop drifts under rotation carry until PHO-59 (the PhaseCue KDoc says so), and the demo's seam tests measure that script. The format supports look steps; the demo doesn't dogfood them yet.
• Phase isn't a step field; a step names a Look. The phase→look table stays with CognitiveLookSwitch.

Verification

./gradlew ktlintFormat :phosphor-lumos:jvmTest :phosphor-trace:jvmTest :phosphor-lumos-compose:jvmTest :phosphor-lumos-cli:jvmTest ktlintCheck --offline green locally. kotlinUpgradeYarnLock / kotlinWasmUpgradeYarnLock ran; no lockfile change. Web, iOS and Dokka are left to CI. The demo was not run interactively.

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