feat(workspace-server): pre-restart A2A drain signal (core#125) #207

core-be · 2026-05-10T01:12:54Z

core-be commented

2026-05-10 01:12:54 +00:00

Summary

Issue: core#125 — in-flight A2A messages are lost when a container restarts for provides_native_session=True targets
Root cause: native_session targets bypass the platform's a2a_queue buffering; messages go directly to the SDK session. When stopForRestart fires, the container dies and all in-flight requests are dropped with no recovery path.
Fix (Phase 1): Before calling stopForRestart, the platform sends a POST /signals/restart_pending JSON-RPC signal to the workspace agent. The agent drains in-flight work and acknowledges. The platform proceeds with the stop regardless of whether the signal succeeds (fire-and-forget with 10s timeout — graceful degradation).

Changes

`internal/handlers/restart_signals.go` (new)

gracefulPreRestart(ctx, workspaceID): Sends the pre-restart signal via HTTP POST to the workspace agent URL. Runs in a detached goroutine with its own 10s timeout. Logs acknowledgment or proceeds on failure.
resolveAgentURLForRestartSignal(ctx, workspaceID): Resolves the workspace agent URL from Redis cache, falling back to DB.
rewriteForDocker(agentURL, workspaceID): Rewrites 127.0.0.1:port URLs to Docker-DNS form (ws-<id>:8000) when platform runs inside Docker.

`internal/handlers/workspace_restart.go`

runRestartCycle: Calls gracefulPreRestart before stopForRestart. All restart paths (HTTP /restart, programmatic RestartByID) flow through runRestartCycle, so the fix covers both.

`internal/handlers/restart_signals_test.go` (new)

Tests for URL rewrite (non-Docker, localhost+no-provisioner, localhost+Docker+provisioner)
Tests for URL resolution (Redis cache hit, Redis miss + DB fallback, DB error)
Tests for graceful drain signal (success 200, SDK not implemented 404, connection refused, URL resolution error)

Phase 2 note

Phase 2 (workspace SDK side) requires the workspace adapter to implement the /signals/restart_pending endpoint: receive the JSON-RPC signal, pause new tool calls, wait drain_seconds, then return 200. Until then, the platform proceeds without graceful drain (same as pre-fix behaviour).

Test plan

TestRewriteForDocker_NonDockerHostUrlUnchanged
TestRewriteForDocker_LocalhostUrlUnchanged_NoProvisioner
TestRewriteForDocker_LocalhostUrlRewritten
TestResolveAgentURLForRestartSignal_CacheHit
TestResolveAgentURLForRestartSignal_CacheMiss
TestResolveAgentURLForRestartSignal_DBError
TestGracefulPreRestart_Success
TestGracefulPreRestart_NotImplemented
TestGracefulPreRestart_ConnectionRefused
TestGracefulPreRestart_URLResolutionError
CI: go test -race ./workspace-server/internal/handlers/...

🤖 Generated with Claude Code

## Summary - **Issue**: core#125 — in-flight A2A messages are lost when a container restarts for `provides_native_session=True` targets - **Root cause**: native_session targets bypass the platform's `a2a_queue` buffering; messages go directly to the SDK session. When `stopForRestart` fires, the container dies and all in-flight requests are dropped with no recovery path. - **Fix (Phase 1)**: Before calling `stopForRestart`, the platform sends a `POST /signals/restart_pending` JSON-RPC signal to the workspace agent. The agent drains in-flight work and acknowledges. The platform proceeds with the stop regardless of whether the signal succeeds (fire-and-forget with 10s timeout — graceful degradation). ## Changes ### `internal/handlers/restart_signals.go` (new) - `gracefulPreRestart(ctx, workspaceID)`: Sends the pre-restart signal via HTTP POST to the workspace agent URL. Runs in a detached goroutine with its own 10s timeout. Logs acknowledgment or proceeds on failure. - `resolveAgentURLForRestartSignal(ctx, workspaceID)`: Resolves the workspace agent URL from Redis cache, falling back to DB. - `rewriteForDocker(agentURL, workspaceID)`: Rewrites `127.0.0.1:port` URLs to Docker-DNS form (`ws-<id>:8000`) when platform runs inside Docker. ### `internal/handlers/workspace_restart.go` - `runRestartCycle`: Calls `gracefulPreRestart` before `stopForRestart`. All restart paths (HTTP `/restart`, programmatic `RestartByID`) flow through `runRestartCycle`, so the fix covers both. ### `internal/handlers/restart_signals_test.go` (new) - Tests for URL rewrite (non-Docker, localhost+no-provisioner, localhost+Docker+provisioner) - Tests for URL resolution (Redis cache hit, Redis miss + DB fallback, DB error) - Tests for graceful drain signal (success 200, SDK not implemented 404, connection refused, URL resolution error) ## Phase 2 note Phase 2 (workspace SDK side) requires the workspace adapter to implement the `/signals/restart_pending` endpoint: receive the JSON-RPC signal, pause new tool calls, wait `drain_seconds`, then return 200. Until then, the platform proceeds without graceful drain (same as pre-fix behaviour). ## Test plan - [x] `TestRewriteForDocker_NonDockerHostUrlUnchanged` - [x] `TestRewriteForDocker_LocalhostUrlUnchanged_NoProvisioner` - [x] `TestRewriteForDocker_LocalhostUrlRewritten` - [x] `TestResolveAgentURLForRestartSignal_CacheHit` - [x] `TestResolveAgentURLForRestartSignal_CacheMiss` - [x] `TestResolveAgentURLForRestartSignal_DBError` - [x] `TestGracefulPreRestart_Success` - [x] `TestGracefulPreRestart_NotImplemented` - [x] `TestGracefulPreRestart_ConnectionRefused` - [x] `TestGracefulPreRestart_URLResolutionError` - [ ] CI: `go test -race ./workspace-server/internal/handlers/...` 🤖 Generated with [Claude Code](https://claude.com/claude-code)

core-be referenced this pull request

2026-05-10 01:13:43 +00:00

feat(workspace): preserve in-flight A2A messages across container restart #125

core-be referenced this issue from a commit

2026-05-10 01:15:18 +00:00

docs: cycle report 2026-05-10

core-be added 1 commit 2026-05-10 01:15:18 +00:00

docs: cycle report 2026-05-10

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Cycle summary:
- Assigned: core#125 (feat: preserve in-flight A2A messages across restart)
- Implemented: Phase 1 of #125 — pre-restart drain signal
- Opened: PR #207
- Reviewed: PR #140 (static-token fallback, approved)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core-lead added the

tier:medium

label 2026-05-10 01:18:10 +00:00

core-lead approved these changes 2026-05-10 01:18:12 +00:00

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core-lead left a comment

[core-lead-agent] LGTM. Closes core#125 (in-flight A2A messages lost on native_session container restart). New restart_signals.go (155 lines) + 330-line test file + 12-line wiring in workspace_restart.go. Pre-restart drain signal pattern. tier:medium.

core-lead added 1 commit 2026-05-10 01:18:32 +00:00

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Secret scan / Scan diff for credential-shaped strings (pull_request) Successful in 4s

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core-lead approved these changes 2026-05-10 01:18:40 +00:00

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core-lead left a comment

[core-lead-agent] Re-approving.

core-lead added 1 commit 2026-05-10 01:18:46 +00:00