feat: cache recent sessions for offline startup

[wolfiesch]

Summary

• persist a bounded, versioned projection snapshot so recent sessions stay visible before the first live host frame arrives
• keep cached sessions authenticated but read-only until live state replaces them, with explicit offline and starting indicators
• make persistence best-effort and drain queued cache writes during shutdown without blocking live projection updates

Verification

• pnpm check
• pnpm test

[chatgpt-codex-connector]

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[Copilot]

Pull request overview

Adds an encrypted, size-bounded projection snapshot cache that can be loaded via Desktop IPC before the first live host frame arrives, allowing “recent sessions” to render immediately on startup while remaining read-only until live state replaces them.

Changes:

• Introduces new Desktop IPC channels for projection-cache load/save with strict payload validation and size limits.
• Wires a projection cache store through the web runtime into the client ProjectionStore, and ensures cache saves drain during shutdown.
• Implements an Electron-backed encrypted cache store (safeStorage + ElectronStore) and integrates it into the desktop lifecycle + IPC registry, with targeted test coverage.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/protocol/src/desktop-ipc.ts	Adds IPC channel declarations and strict decoders for projection cache load/save payloads and results.
packages/protocol/test/desktop-ipc.test.ts	Adds protocol-boundary tests covering versioning, size bounds, and invalid payload rejection for projection cache IPC.
packages/client/src/projection.ts	Ensures coalesced cache snapshots continue draining even after dispose begins (shutdown flush behavior).
packages/client/test/projection.test.ts	Extends projection store tests to validate async cache-save draining through dispose/shutdown.
packages/client/src/projection-cache.ts	Centralizes MAX_PROJECTION_CACHE_BYTES by importing it from protocol and re-exporting it for client usage.
packages/client/src/desktop-runtime.ts	Awaits projection hydration (projection.ready()) before bootstrapping the shell to enable offline-first startup.
packages/client/src/desktop-runtime-contracts.ts	Extends the shell port contract with projection cache load/save operations.
apps/web/src/platform/desktop-runtime.ts	Wires desktop shell cache load/save into a ProjectionCacheStore, and injects a cached ProjectionStore into the runtime controller.
apps/web/test/live-composer.test.ts	Adds integration test verifying hydration from shell cache and later persistence of live mutations.
apps/desktop/src/ipc.ts	Adds IPC handlers for app:projection-cache:load/save with sender assertion and protocol decoding/encoding.
apps/desktop/test/ipc-lifecycle.test.ts	Adds lifecycle proof test that projection cache IPC routes through the trusted shell service and rejects extra fields.
apps/desktop/src/stores.ts	Implements ElectronProjectionCacheStore using safeStorage encryption + bounded base64 state validation + serialized writes.
apps/desktop/test/stores-lifecycle.test.ts	Adds tests for encrypted-at-rest behavior, degradation when encryption unavailable, corruption clearing, and concurrent save serialization.
apps/desktop/src/lifecycle.ts	Creates a single projection cache after app readiness and injects it into IPC runtime bindings across windows.
apps/desktop/test/lifecycle-runtime.test.ts	Tests that projection cache is created once post-readiness and reused across subsequent runtime bindings.
apps/desktop/src/preload.ts	Adds preload bridge methods for projection cache load/save and decodes results via protocol validators.

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[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 1 comment.