[kahrendt]

Summary

A client's available and the join a turn to available: true makes for its stream roles lived in PlayerStream, whatever roles the client had, and ServerCore read them as session().player().available(). That placement made a visualizer-only client's join look missing. It was not: PlayerStream set the join for every client, and Session applies the kind to both stream roles. This moves the decision to the session, where it belongs. Behavior is unchanged.

Change

• Session::on_client_state decides the join: a report of available: true that is the first or follows false. Session::available() exposes the latest report.
• PlayerStream drops its state_received_, its availability join and its available() accessor. Its on_client_state returns a kind only for the role's first object since its activation, as VisualizerStream's does.
• PlayerStream and VisualizerStream each keep their copy of available for eligibility, as ArtworkStream and SourceStream do.
• ServerCore::on_client_state reads session().available().
• Left as is: the two streams' near-identical on_activation_written() bodies. The visualizer's also resets its offset_.

Tests

• SessionTest.MakesATurnToAvailableAJoin: a table over Session with no I/O, on a visualizer-only client. Each row's last client/state carries no role object, so any join is availability's. It covers true after false (Control), a first true, true after true, false after true and a first false. The "true after true" row covers the old rule, which had no test.
• ServerVisualizer.JoinsAPlayingGroupOnceItTurnsAvailable: a visualizer-only client whose first client/state reports available: false stays in the playing group it joined. Once it reports true, its stream starts the group lead past its stream/start. The check of the first message against the lead is shared with StartsAJoinerTheGroupLeadPastItsStart.
• Known gap: the raw-client test guards the join rule only weakly. The first state's own join (the role's first object) may still be pending when available: true arrives, so the Session test holds the rule.

Closes #26

[Copilot]

🟢 Approval recommended

The focused refactor preserves existing semantics, updates the affected caller, and adds regression coverage with no identified blocking issues.

0 open findings

What changed in this PR

Moves client availability and availability-triggered joins into Session, preserving behavior while clarifying ownership for visualizer-only clients.

Changes:

• Centralizes availability tracking and join decisions in Session.
• Removes session-wide availability responsibilities from PlayerStream.
• Adds session regression coverage and a visualizer integration test.

File	Description
tests/​test_session.cpp	Tests availability transitions and join decisions.
tests/​test_server_visualizer.cpp	Tests availability-driven startup and shares timing assertions.
src/​session.h	Adds session availability state and accessor.
src/​session.cpp	Decides availability-triggered joins.
src/​server_core.cpp	Reads availability directly from the session.
src/​player_stream.h	Removes the availability accessor and redundant tracking field.
src/​player_stream.cpp	Limits join decisions to the role’s first state object.

🧠 Review effort: Balanced

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