feat(server): add onPeerDisconnect, symmetric with onPeerConnect

[dvcolomban]

What

startHttpAndWs's onDisconnected handler consumed the transport's own disconnect entirely — it only fed rpcHost._emitSessionDisconnected(meta) — leaving callers with no way to observe a peer going away. The only socket-close hook that exists is host-functions.ts's _emitSessionDisconnected, and its own docblock says it's @internal and "must not" widen the public surface. Meanwhile onPeerConnect (the connect-time counterpart) is already public.

This adds onPeerDisconnect?: (peer, meta) => void, forwarded verbatim to the underlying startHttpAndWs. Unlike onPeerConnect it receives the raw session meta, not a wrapped session — by the time a peer disconnects there's no live RPC client left to attach.

createDevServer never forwarded either hook down to startHttpAndWs at all, so this also adds a passthrough onPeerConnect option there for parity — today a createDevServer caller has no way to reach either callback.

Why this matters

Any host that tracks per-peer state outside the RPC layer (a registry keyed by connection, a presence list, cleanup for something the peer owned) currently has no first-party way to know a peer left — it either reaches for the internal, explicitly-not-for-this _emitSessionDisconnected, or leaks that state forever.

Tests

Two new cases:

• packages/devframe/src/node/__tests__/server.test.ts: startHttpAndWs forwards both hooks for the same peer — onPeerConnect fires on open, onPeerDisconnect fires on close with matching session meta (meta.id), and neither fires early.
• packages/devframe/src/adapters/__tests__/dev.test.ts: createDevServer forwards both options down to startHttpAndWs end to end.

Both verified to fail (0 calls recorded) against the pre-fix code before adding the guard/forwarding.

pnpm --filter devframe exec vitest run — 49 files, 448 tests, all green. tsc --noEmit clean. eslint clean.

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[Copilot]

🟡 Changes recommended

onPeerDisconnect currently receives a meta object after internal disconnect cleanup mutates it, which can undermine the “raw session meta” semantics for consumers.

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Pull request overview

This PR adds a public disconnect-time peer hook to the devframe node WebSocket server (startHttpAndWs) and plumbs both connect/disconnect peer hooks through createDevServer, enabling hosts to react to peer lifecycle events without reaching into @internal APIs.

Changes:

• Added onPeerDisconnect to StartHttpAndWsOptions and invoked it from the WS transport onDisconnected handler.
• Added onPeerConnect/onPeerDisconnect passthrough options to createDevServer.
• Added vitest coverage for hook forwarding at both the startHttpAndWs and createDevServer layers.

File summaries

File	Description
packages/devframe/src/node/server.ts	Adds onPeerDisconnect option and wires it into the WS disconnect hook.
packages/devframe/src/node/tests/server.test.ts	Verifies startHttpAndWs fires connect + disconnect hooks for the same session.
packages/devframe/src/adapters/dev.ts	Exposes and forwards peer hook options through createDevServer.
packages/devframe/src/adapters/tests/dev.test.ts	Verifies createDevServer forwards both hooks to startHttpAndWs.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Lite

We're testing this review assessment. Please use 👍 or 👎 to tell us if it's correct.

[Copilot]

🟡 Changes recommended

A user-provided onPeerDisconnect callback can currently prevent internal disconnect cleanup from running if it throws, risking leaked per-session state.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

This review doesn't count toward merge requirements. Sign up for the private preview to control whether Copilot approvals count.

Review details

Suppressed comments (2)

packages/devframe/src/node/server.ts:237

• onPeerDisconnect runs before rpcHost._emitSessionDisconnected(meta). If a consumer callback throws, the internal disconnect cleanup (notably streaming cleanup) will be skipped because attachWsRpcTransport does not guard onDisconnected. Wrap the internal cleanup in a finally so it always runs.

    onDisconnected: (peer, meta) => {
      options.onPeerDisconnect?.(peer, meta)
      rpcHost._emitSessionDisconnected(meta)
    },

packages/devframe/src/adapters/dev.ts:101

• The docstring says onPeerDisconnect runs "right after its session's disconnect bookkeeping runs", but startHttpAndWs invokes the hook before devframe's own session cleanup (_emitSessionDisconnected). Update the wording to match the actual ordering/semantics.

  /**
   * Called once per closed WS connection, right after its session's
   * disconnect bookkeeping runs. Forwarded verbatim to the underlying
   * `startHttpAndWs`.
   */

• Files reviewed: 4/5 changed files
• Comments generated: 0 new
• Review effort level: Lite

We're testing this review assessment. Please use 👍 or 👎 to tell us if it's correct.

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