Layered VM resource management: cgroup isolation, monitoring, eviction

[simple-agent-manager]

Summary

• Step 1 — Protect vm-agent: OOMScoreAdjust=-900 + systemd slice in cloud-init. Docker gets a configurable MemoryMax budget via systemd override (VM_AGENT_MEMORY_RESERVE_MB, default 768MB), ensuring the vm-agent process survives container OOM pressure.
• Step 2 — Active resource monitoring: PSI (Pressure Stall Information) parser + Docker OOM/die-137 event subscription in a unified ResourceGuard goroutine. Exposes PressureEvents() <-chan PressureEvent for consumers. All thresholds env-configurable with DEFAULT_* constants.
• Step 3 — Pre-stop snapshot + eviction: Eviction controller subscribes to ResourceGuard pressure events, selects the largest memory consumer, captures a session snapshot (before docker stop — snapshot commands run inside containers), stops the container, and POSTs an eviction callback to the control plane. Callback route uses callback JWT auth (rule 34), mounted before projectsRoutes. Adds evicted workspace status.

Step 4 (control-plane rescheduling) is captured as SAM idea 01M190M3EQK3PFXRKR3DTF7Q8K only — not implemented in this PR.

Validation

• pnpm lint
• pnpm typecheck
• pnpm test
• Additional validation run (if applicable)
• If this PR changes candidate selection for a sweep/cron/alarm loop: N/A — no sweep/cron changes

Staging Verification (REQUIRED for all code changes — merge-blocking)

• Staging deployment green — Deploy Staging run 33401872268 passed for sam/layered-resource-management
• Live app verified via Playwright — Chromium shared libraries unavailable in this workspace; verified via API curl checks. No UI changes in this PR (apps/web/ only adds evicted status type and minor hook type guard).
• Existing workflows confirmed working — API health endpoint returns {"status":"healthy"}, staging deploy smoke tests passed
• New feature/fix verified on staging — Eviction callback route deployed and returns 401 on unauthenticated request (proves route exists and uses callback JWT auth, not session auth). Cloud-init and vm-agent changes require fresh node provisioning (rule 27) to verify on live VMs.
• Infrastructure verification completed — staging deploy includes new vm-agent binary uploaded to R2. Full VM provisioning verification requires fresh node (rule 27); cloud-init template tested with 220 lines of unit tests including realistic PEM data.
• Mobile and desktop verification notes: N/A — no UI changes

Staging Verification Evidence

• Staging deploy: run 33401872268 (success, all jobs green including smoke tests)
• API health: curl https://api.sammy.party/health → {"status":"healthy","timestamp":"2026-08-31T14:39:20.586Z"}
• Eviction callback route: curl https://api.sammy.party/api/projects/test/workspaces/test/eviction → 401 (callback JWT auth working correctly)

UI Compliance Checklist (Required for UI changes)

N/A: no UI changes. The only apps/web/ modifications are adding evicted to the workspace status type guard in useWorkspacePorts.ts and the API client types.

End-to-End Verification (Required for multi-component changes)

• Data flow traced from user input to final outcome with code path citations
• Capability test exercises the complete happy path across system boundaries
• All spec/doc assumptions about existing behavior verified against code
• Manual verification steps documented for gaps

Data Flow Trace

1. Memory pressure detected by kernel
   → packages/vm-agent/internal/resourcemon/pressure.go:parsePSI() reads /proc/pressure/memory
   → guard.go:monitorPSI() checks thresholds

2. OR Docker OOM kill event
   → docker_events.go:Subscribe() listens for event=oom and event=die with exit code 137
   → guard.go:monitorDocker() processes events

3. ResourceGuard emits PressureEvent
   → guard.go:PressureEvents() channel delivers to consumers

4. Eviction controller receives event
   → eviction.go:handlePressureEvent() debounces, acquires mutex
   → eviction.go:selectEvictionTarget() picks largest memory consumer
   → eviction.go:evictContainer() captures snapshot, stops container

5. Server-side eviction integration
   → server/eviction.go:handleEviction() resolves workspace/session from container
   → Captures session snapshot via captureHibernateSnapshot() with captured ACP identity (rule 49)
   → Marks runtime state as evicted
   → POSTs callback to control plane

6. Control plane receives eviction callback
   → routes/projects/workspace-eviction-callback.ts validates callback JWT (rule 34)
   → Validates workspace ownership
   → Transitions workspace status to evicted
   → Broadcasts status update via WebSocket

Untested Gaps

• Full live VM eviction flow requires a real node under memory pressure — tested via unit/integration tests with mocked Docker/PSI interfaces. The eviction controller + server integration is exercised end-to-end in Go tests.
• Step 4 (control-plane rescheduling after eviction) is not implemented — tracked as idea 01M190M3EQK3PFXRKR3DTF7Q8K.

Post-Mortem (Required for bug fix PRs)

N/A: not a bug fix. New feature implementation.

Agent Preflight (Required)

• Preflight completed before code changes

Classification

• cross-component-change
• infra-change

External References

• Linux PSI documentation: https://docs.kernel.org/accounting/psi.html
• Docker events API: standard Docker Engine API
• systemd resource control: systemd.resource-control(5)

Codebase Impact Analysis

• packages/cloud-init/ — systemd slice + MemoryMax override generation
• packages/vm-agent/internal/resourcemon/ — new package: PSI parser, Docker events, container metrics, ResourceGuard, eviction controller
• packages/vm-agent/internal/server/ — eviction integration, snapshot coordination enhancements
• packages/vm-agent/internal/config/ — resource monitoring configuration
• apps/api/src/routes/projects/workspace-eviction-callback.ts — new callback route
• apps/api/src/index.ts — callback route mounting
• packages/shared/src/constants/status.ts — evicted workspace status
• apps/www/src/content/docs/ — configuration reference updates

Documentation & Specs

• apps/www/src/content/docs/docs/reference/configuration.md — updated with new env vars
• apps/www/src/content/docs/docs/reference/vm-agent.md — updated with resource monitoring docs

Constitution & Risk Check

All thresholds, timeouts, and limits use DEFAULT_* constants with env var overrides per Principle XI:

• DEFAULT_VM_AGENT_MEMORY_RESERVE_MB (768)
• DEFAULT_RESOURCE_MON_PSI_POLL_INTERVAL_MS (5000)
• DEFAULT_RESOURCE_MON_PSI_SOME_THRESHOLD (25.0)
• DEFAULT_RESOURCE_MON_PSI_FULL_THRESHOLD (10.0)
• DEFAULT_RESOURCE_MON_EVICTION_DEBOUNCE_MS (5000)
• DEFAULT_RESOURCE_MON_EVICTION_COOLDOWN_MS (30000)

Specialist Review Evidence

Reviewer	Status	Notes
go-specialist	PASS	PR #1971, #1975 reviewed — concurrency patterns, mutex usage, channel lifecycle
cloudflare-specialist	PASS	PR #1975 reviewed — callback route auth, D1 patterns
security-auditor	PASS	PR #1975 reviewed — callback JWT auth, workspace ownership validation
test-engineer	PASS	PR #1971, #1975 reviewed — test coverage, regression patterns
constitution-validator	PASS	All values env-configurable with DEFAULT_* constants
doc-sync-validator	PASS	Configuration reference and vm-agent docs updated

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

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_{Comparing sam/layered-resource-management (c98c863) with main (78d29db)}

[sonarqubecloud]

Quality Gate failed

Failed conditions
B Security Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

Catch issues before they fail your Quality Gate with our IDE extension SonarQube for IDE

[raphaeltm]

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📥 Commits

Reviewing files that changed from the base of the PR and between 78d29db and c98c863.

📒 Files selected for processing (64)

• .agents/skills/env-reference/SKILL.md
• .claude/skills/api-reference/SKILL.md
• .claude/skills/env-reference/SKILL.md
• apps/api/.env.example
• apps/api/src/durable-objects/project-data/runtime-heartbeat-policy.ts
• apps/api/src/durable-objects/vm-agent-container-runtime.ts
• apps/api/src/env.ts
• apps/api/src/index.ts
• apps/api/src/routes/projects/workspace-eviction-callback.ts
• apps/api/src/routes/workspaces/ports-readiness.ts
• apps/api/src/services/compute-usage.ts
• apps/api/src/services/nodes.ts
• apps/api/src/services/vm-prompt-delivery-adapter.ts
• apps/api/tests/unit/services/provision-node-rethrow.test.ts
• apps/api/tests/workers/route-auth-validation.test.ts
• apps/api/wrangler.toml
• apps/web/src/hooks/useWorkspacePorts.ts
• apps/web/src/lib/api/workspaces.ts
• apps/web/tests/unit/hooks/workspace-running-status.test.ts
• apps/www/src/content/docs/docs/reference/configuration.md
• apps/www/src/content/docs/docs/reference/vm-agent.md
• packages/cloud-init/src/generate.ts
• packages/cloud-init/src/template.ts
• packages/cloud-init/tests/generate.test.ts
• packages/shared/src/constants/status.ts
• packages/shared/src/types/workspace.ts
• packages/shared/src/vm-agent-contract.ts
• packages/vm-agent/.env.example
• packages/vm-agent/internal/config/config.go
• packages/vm-agent/internal/config/config_load.go
• packages/vm-agent/internal/config/config_test.go
• packages/vm-agent/internal/config/helpers.go
• packages/vm-agent/internal/config/resource_monitoring.go
• packages/vm-agent/internal/container/discovery.go
• packages/vm-agent/internal/container/discovery_test.go
• packages/vm-agent/internal/persistence/store.go
• packages/vm-agent/internal/persistence/store_test.go
• packages/vm-agent/internal/resourcemon/container_metrics.go
• packages/vm-agent/internal/resourcemon/container_metrics_test.go
• packages/vm-agent/internal/resourcemon/docker_events.go
• packages/vm-agent/internal/resourcemon/docker_events_test.go
• packages/vm-agent/internal/resourcemon/eviction.go
• packages/vm-agent/internal/resourcemon/eviction_test.go
• packages/vm-agent/internal/resourcemon/guard.go
• packages/vm-agent/internal/resourcemon/guard_test.go
• packages/vm-agent/internal/resourcemon/pressure.go
• packages/vm-agent/internal/resourcemon/pressure_test.go
• packages/vm-agent/internal/server/eviction.go
• packages/vm-agent/internal/server/eviction_test.go
• packages/vm-agent/internal/server/git.go
• packages/vm-agent/internal/server/server.go
• packages/vm-agent/internal/server/session_snapshot.go
• packages/vm-agent/internal/server/session_snapshot_container_support.go
• packages/vm-agent/internal/server/session_snapshot_coordinator.go
• packages/vm-agent/internal/server/session_snapshot_coordinator_test.go
• packages/vm-agent/internal/server/session_snapshot_test.go
• packages/vm-agent/internal/server/workspace_routing.go
• packages/vm-agent/internal/server/workspaces.go
• packages/vm-agent/internal/sysinfo/sysinfo.go
• packages/vm-agent/internal/sysinfo/sysinfo_test.go
• scripts/deploy/sync-wrangler-config.ts
• tasks/active/2026-08-30-vm-agent-active-resource-monitoring.md
• tasks/active/2026-08-30-vm-agent-cgroup-resource-isolation.md
• tasks/archive/2026-08-30-pre-stop-eviction-snapshots.md

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