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+# Session Log – ZeroLagHub (Execution Ledger)
+
+Chronological ledger of notable execution work. Keep this high signal.
+
+---
+
+## 2026-03-01 – Upload Pipeline + Filesystem Consolidation
+
+### Completed
+
+- Implemented direct runtime upload model
+- Removed staging and symlink exploration
+- Added `.zlh_metadata.json` provenance tracking
+- Extended `stat` response with `source`
+- Implemented raw `http.request` streaming in API
+- Confirmed agent upload via direct curl
+- Identified API upload proxy transport timing issue
+- Switched from `fetch()` to native piping
+- Consolidated filesystem architecture docs (`filesystem-and-file-browser.md`, `mod-deployment-safety.md`)
+- Full grind repo consolidation pass (README, CONSTRAINTS, OPEN_THREADS, SESSION_START, ANTI_DRIFT, UPSTREAMS)
+
+### System State
+
+- Read: Stable
+- Write: Stable with shadow backup
+- Delete: Constrained and safe
+- Upload: Implemented, transport tuning in progress
+- Console: Stable
+
+### Remaining Focus
+
+- Improve upload transport diagnostics
+- Increase upload timeout
+- Dev server filesystem model planning
+
+---
+
+## 2026-02-23 – Mod System Now Operational
+
+Full mod lifecycle implemented and confirmed end-to-end.
+
+### What shipped
+- Modrinth search integrated (`GET /api/game/mods/search`)
+- Full install/list/enable/disable/delete routes live behind auth + ownership
+- Agent host allowlist expanded to include `cdn.modrinth.com`
+- Filename validation updated to allow `+` (required for Modrinth filenames like `sodium-neoforge-0.6.13+mc1.21.4.jar`)
+- Engine metadata bug fixed: `engineType="neoforge"`, `engineVersion="1.21.4"` (was `"minecraft"` / `"neoforge-1.21.4"`)
+- API → Agent payload contract corrected (field names and `source` field)
+- Frontend: mod search drawer, installed panel, enable/disable/delete, toast notifications
+
+### System state
+- Full lifecycle via API: ✅
+- Frontend search + install: ✅
+- Enable/disable/delete: ✅
+- Installed flag displayed: ✅
+- Soft delete to `/mods-removed`: ✅
+- No retention automation: intentional
+- No install queue: intentional
+- Filesystem authoritative: confirmed
+
+### Known tradeoffs locked in
+- No deterministic Modrinth project ID persistence (installed detection is heuristic)
+- No DB tracking of mod state
+- Soft delete is permanent until file browser enables manual restore
+
+### Pending
+- Response corruption investigation (one early curl output appeared malformed)
+- API error mapping: `"mod already exists"` → `409` (currently `502`)
+- Portal UI wiring for install flow
+
+---
+
+## 2026-02-22 – Architecture strategy session (Claude)
+
+### Artifact server strategy decided
+- Moved away from self-hosting all mod artifacts.
+- `zlh-artifactd` Phase 1 scope: **mod resolver only** (Modrinth API + NeoForge maven).
+  - No local mod storage in Phase 1; agent fetches from upstream, verifies hash.
+  - Local caching added in Phase 2 based on real usage patterns.
+- Full artifact orchestrator (game jars, runtimes, mods unified) is the Phase 3 vision.
+- Rationale: single-operator sustainability; learn ingestion patterns from mods before automating game jars.
+
+### Mod platform decision
+- **Modrinth** as primary source (open API, no key required, hash provided, NeoForge/Fabric/Forge/Quilt filter support).
+- **CurseForge**: manual SFTP upload by user (their friction, not ours).
+- Modrinth API base: `api.modrinth.com/v2`, rate limit 300 req/min, requires User-Agent header.
+
+### NeoForge versions for artifact server
+- **1.21.1** – highest mod ecosystem density (16,000+ mods)
+- **1.21.4** – next significant stable adoption
+- **1.21.11** – current latest
+- 1.20.x NOT needed for NeoForge; existing Forge covers that ecosystem.
+
+### Vanilla MC versions to add
+- Currently at 1.21.7; need to add 1.21.8 through 1.21.11.
+- Source: Mojang version manifest at `piston-meta.mojang.com/mc/game/version_manifest_v2.json`.
+
+### Confirmed loader coverage at launch
+- Vanilla, Paper, Purpur, Forge, Quilt (covers Fabric mods too) – already in place.
+- NeoForge added (3 versions above).
+- No Fabric standalone needed; Quilt provides compatibility.
+
+---
+
+## 2026-02-21 → 2026-02-22 – Game telemetry routing + agent Phase 1 feature set
+
+### API (control plane)
+- Added `src/routes/game.js`, mounted at `/api/game`.
+- Added:
+  - `GET /api/game/servers/:id/players` (Redis-backed, normalized response)
+  - `GET /api/game/servers/:id/update-status` (agent version + update state)
+- Extended `src/utils/agentPoller.js`:
+  - poll agent `GET /game/players` for game containers
+  - poll agent `GET /version` + `GET /agent/update/status`
+  - cache `agentVersion`, `updateStatus`, `updateAvailable`
+- Persisted `engineType`/`engineVersion` in `ContainerInstance` on provisioning.
+- Rolled back provisioning-time agent update triggers (back to direct `/config` flow).
+
+### Frontend (portal)
+- Game console polling switched to:
+  - `GET /api/game/servers/:id/players`
+  - `GET /api/game/servers/:id/update-status`
+- UI shows player count + optional name list.
+- Version context rendered as `Version: X` or `Version: X -> Y`.
+
+### Agent (runtime)
+- `/game/players` hardened for more reliable Minecraft presence (port/protocol fallbacks).
+- Added periodic update checks:
+  - `ZLH_AGENT_UPDATE_MODE=notify|auto|off`
+  - `ZLH_AGENT_UPDATE_INTERVAL` (default `30m`)
+- Implemented Phase 1 mod management:
+  - `GET /game/mods`
+  - `POST /game/mods/install` (allowlist + redirect constraints + size cap + sha256 verify)
+  - `PATCH /game/mods/:mod_id` (enable/disable)
+  - `DELETE /game/mods/:mod_id` (moves to `mods-removed/`)
+- Implemented `GET /metrics/process` (PID + VmRSS/VmSize; restart_count mapped to crashCount).
+- Added Minecraft readiness probe after start/restart and stop-wait-before-restart sync to reduce restart races.
+- Added `lifecycle.log` for lifecycle/probe diagnostics.
+
+### Artifacts
+- Expanded Minecraft artifact tree to include **NeoForge** under `/opt/zlh/zpacks/minecraft/neoforge/<mc_version>/`.
+- Encountered installer naming contract mismatch; Phase 1 fix is to normalize the NeoForge installer filename for predictable installs.
+
+---
+
+## 2026-02-07 → 2026-02-08 – Console stabilization
+- Migrated console from log tailing to **PTY-backed interactive console** over WebSockets.
+- Hardened WS stability:
+  - moved to a single-writer pattern
+  - ensured exactly one PTY read loop per `{vmid, container_type}`
+- Fixed "it works but not on prod" issues caused by stale binaries still running.
+- Confirmed systemd points to `/opt/zlh-agent/current/zlh-agent` with `current -> releases/<ver>` layout.