fix(pi-plugin): support pi-web multi-session and RPC hosts

[elrond298]

Summary

This PR adapts the Pi plugin for pi-web, where multiple Pi sessions share one persistent Node.js process and commands run through Pi’s RPC mode.

It addresses shared-process session isolation, duplicate startup work, unsafe subagent CLI detection, RPC command feedback, and /ctx-dream failures before the first model turn.

Changes

Session isolation

• Replace the process-global child-session flag with an AsyncLocalStorage<boolean> marker.
• Update the marker through the public subagents:child:session-created and subagents:child:disposed events.
• Suppress initialization only for in-process child subagents.
• Allow independent sessions in the same pi-web process to initialize normally.
• Remove child lifecycle listeners during session_shutdown to prevent stale handlers after reloads.

Process-wide startup maintenance

• Claim deferred startup maintenance once per process.
• Schedule the legacy-memory identity rekey introduced by database migration v22 only once per process.
• Schedule the session-to-project mapping backfill only once per process.
• Load session history only after acquiring the durable backfill lease, avoiding redundant JSONL scans.

Safer subagent CLI detection

• Reuse process.argv[1] only when it identifies a supported Pi CLI; otherwise use the packaged executable, bundled CLI, or PATH fallback as appropriate.
• This prevents embedded hosts such as Next.js from accidentally launching another web server when creating a subagent.

RPC command presentation

• Preserve model-invisible command entries while presenting them through the RPC UI.
• Show short progress updates through ctx.ui.notify.
• Show formatted results in modal dialogs through ctx.ui.custom.
• Apply this behavior to /ctx-status, /ctx-embed, /ctx-recomp, /ctx-session-upgrade, and /ctx-dream.

Dreamer registration

• Track Dreamer registration ownership per Pi extension instance.
• Prevent one session’s shutdown from deregistering a same-project sibling.
• Transfer the active registration to a remaining worktree owner when necessary.
• Synchronize the current project’s Dreamer registration immediately before a manual /ctx-dream run.
• This allows /ctx-dream to work before the first before_agent_start event.

Verification

• bun run --cwd packages/pi-plugin build
• bun run --cwd packages/pi-plugin test — 804 passed, 0 failed
• bun test packages/plugin/src/features/magic-context/session-project-backfill.test.ts — 9 passed, 0 failed
• git diff --check

Regression coverage includes:

• independent same-process sessions versus child-session suppression
• lifecycle listener cleanup during shutdown
• process-wide startup maintenance claimed through full runtime initialization
• lazy backfill lease gating without session-history reads
• owner-aware Dreamer registration, shutdown isolation, and ownership transfer
• single-timer Dreamer handoff when remaining owners repeat a worktree directory
• embedded-host Pi CLI discrimination
• RPC notification and modal-dialog routing
• pre-execution /ctx-dream registration synchronization

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Summary by cubic

Adds pi-web multi-session and RPC support to packages/pi-plugin and stabilizes Dreamer owner handoff. Old behavior suppressed all same‑process inits via a global latch; new behavior suppresses only in‑process child subagents via lifecycle‑scoped AsyncLocalStorage, runs startup maintenance once per process, and avoids re‑running embedded hosts.

• In‑process child guard: mark child sessions via subagents:child:session-created/subagents:child:disposed on an AsyncLocalStorage context; only marked children no‑op; independent same‑process sessions initialize normally. Unsubscribe lifecycle listeners on session_shutdown.
• Process‑wide startup tasks: claim once per process. Run v22 legacy‑memory rekey and session→project backfill only once; defer session‑history reads until the backfill lease is acquired.
• Safer subagent CLI resolution: reuse process.argv[1] only when it is a Pi CLI (@earendil-works/pi-coding-agent/dist/cli.js). Otherwise use the packaged binary, bundled CLI, or pi on PATH. Never spawn with a shell; prevents embedded hosts (e.g., Next.js) from re‑running themselves.
• RPC command presentation: keep model‑invisible ctx-status entries and present them in RPC. Short progress → ctx.ui.notify; detailed results or rpcDisplay: "dialog" → modal via ctx.ui.custom. Applied to /ctx-status, /ctx-embed, /ctx-recomp, /ctx-session-upgrade, and /ctx-dream. RPC presenter is set only in RPC mode.
• Dreamer registration ownership: track owners per extension instance and per project. One session’s shutdown no longer deregisters a sibling. On active‑owner exit, rebuild once from the most recent remaining owner (worktree handoff handled even when dirs repeat). registerCtxDreamCommand accepts ensureRegistered to sync before manual runs.

Review notes

• Verify only marked children are suppressed and that lifecycle listeners are removed on shutdown.
• Confirm once‑per‑process gating for startup tasks and that session‑history reads occur only after the backfill lease.
• Check CLI discrimination: Pi hosts reuse their CLI; embedded hosts fall back correctly; no shell spawn.
• Exercise RPC rendering: notification vs dialog behavior, and rpcDisplay: "dialog" across updated commands.
• Validate Dreamer owner map and handoff: sibling survival, worktree switch rebuild, and safe unregister when the last owner leaves.

^{Written for commit 72dc718. Summary will update on new commits.}

Greptile Summary

This PR adapts the Pi plugin for multiple sessions sharing one process and for RPC-based hosts.

• Replaces global child-session suppression with lifecycle-scoped detection.
• Coordinates startup maintenance and Dreamer registration across extension instances.
• Adds RPC notifications and dialogs for command output.
• Tightens child CLI selection for embedded hosts.

Confidence Score: 5/5

The PR appears safe to merge because no blocking failure remains within the eligible follow-up-review scope.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/pi-plugin/src/index.ts	Reworks child-session detection, process-wide maintenance, RPC presentation, Dreamer ownership wiring, and shutdown cleanup for persistent multi-session hosts.
packages/pi-plugin/src/dreamer/index.ts	Adds owner-aware project registration and active-owner handoff to preserve Dreamer scheduling across sibling sessions.
packages/pi-plugin/src/subagent-runner.ts	Restricts argv-based CLI reuse and introduces packaged, bundled, and PATH fallback resolution for child processes.
packages/pi-plugin/src/commands/pi-command-utils.ts	Adds RPC presenters, notification-versus-dialog routing, and a modal status component while retaining model-invisible entries.
packages/pi-plugin/src/commands/ctx-dream.ts	Synchronizes Dreamer registration immediately before manual execution and presents completed results through RPC dialogs.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  Host[Persistent Pi or pi-web host] --> SessionA[Extension instance A]
  Host --> SessionB[Extension instance B]
  SessionA --> Shared[Shared process state and SQLite]
  SessionB --> Shared
  SessionA --> OwnerMap[Dreamer owner registry]
  SessionB --> OwnerMap
  SessionA --> RPC[RPC notifications and dialogs]
  SessionB --> RPC
  SessionA --> Child[Resolved Pi child CLI]
  SessionB --> Child

Loading

_{Reviews (2): Last reviewed commit: "fix(pi-plugin): stabilize Dreamer owner ..." | Re-trigger Greptile}

Context used:

• Knowledge Base — Pi plugin runtime: adapting Magic Context to Pi

[cubic-dev-ai]

All reported issues were addressed across 17 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

1 issue found across 17 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/pi-plugin/src/dreamer/index.ts">

<violation number="1" location="packages/pi-plugin/src/dreamer/index.ts:129">
P2: When a stable owner re-registers after a later worktree change, `Map.set` keeps its original insertion position, so shutdown handoff can select a stale sibling checkout. Delete the owner key before setting it to preserve registration recency.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P2: When a stable owner re-registers after a later worktree change, Map.set keeps its original insertion position, so shutdown handoff can select a stale sibling checkout. Delete the owner key before setting it to preserve registration recency.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/pi-plugin/src/dreamer/index.ts, line 129:

<comment>When a stable owner re-registers after a later worktree change, `Map.set` keeps its original insertion position, so shutdown handoff can select a stale sibling checkout. Delete the owner key before setting it to preserve registration recency.</comment>

<file context>
@@ -121,8 +125,12 @@ export function registerPiDreamerProject(opts: PiDreamerOptions): void {
 
 	const existing = registeredProjects.get(opts.projectIdentity);
+	const owners = existing?.owners ?? new Map<object, PiDreamerOptions>();
+	owners.set(opts.registrationOwner, opts);
 	if (existing) {
 		// Same identity, same directory → genuinely already registered, no-op.
</file context>

[alfonso-magic-context]

Thanks for this — especially as a first contribution. The diagnosis is right: the #247 process-global latch is what makes the second pi-web session skip Magic Context entirely, and routing child suppression through subagents:child:session-created/disposed plus AsyncLocalStorage is the correct seam. Once-per-process startup maintenance, not reusing a non-Pi argv[1], Dreamer sibling ownership, and keeping ctx-status entries model-invisible while presenting them in RPC are all the right instincts. And noted that you already pushed the Dreamer owner-handoff stabilization mid-review — that resolves one of the items we had flagged, and that kind of responsiveness makes this easy to shepherd.

Two clarifications so we don't talk past each other:

1. "RPC hosts" here is Pi RPC mode (ctx.ui.notify/ctx.ui.custom). It does not change Magic Context's RPC server, which must stay on 127.0.0.1 with a bearer token. We checked; this PR does not touch that.
2. The old "second init in the process is a no-op" test should change — that contract is the bug for pi-web. Please keep the child-only skip test (you did).

Before we can merge:

• Dreamer registeredProjects on globalThis (same jiti moduleCache:false reason as the child marker), so two sessions in one repo don't start two timers.
• session_shutdown draining only that session's in-flight work — in pi-web, shutdown is not process exit.
• RPC presentation using the command's live ctx, not a session_start closure.
• The #177 "never spawn bare pi" test kept alongside the new embedded-host test.
• packages/pi-plugin/PARITY.md updated for RPC dialogs, the multi-session process model, and the latch → ALS change.

We've approved CI for this PR so your next push gets the full check suite. Really solid work — happy to re-review quickly.