Three coordinated fixes that together close the "ESP-IDF compile takes
5-7 min every time" gap and prevent the failure mode where a user clicking
compile multiple times spawns six ninja processes that peel each other
apart on a modest VPS.
What was wrong
- /compile/start generated a fresh uuid4 every call, so 6 clicks = 6
independent builds racing each other. Saw load average 30 on the prod
VPS during a real BMP280 attempt today.
- No concurrency limit anywhere; asyncio.create_task() fired without
gating.
- ccache was wired in last week (PR #149) but reported 18,350 cacheable
calls and **0 hits** because the build dir was a fresh
tempfile.TemporaryDirectory(prefix='espidf_') per compile. The random
/tmp/espidf_<random>/ path baked into -I and -fmacro-prefix-map flags
→ different command line every compile → ccache hash miss every time.
What this PR does
1. Job deduplication (`backend/app/api/routes/compile.py`)
- New `_job_key(files, board_fqbn)` returns SHA-256 of normalised file
names + contents + board. Order-independent.
- New `JOB_BY_KEY: dict[str, str]` indexes hash → job_id.
- `compile_start` checks JOB_BY_KEY before spawning a new task; if a
job for this exact content is already pending or running, returns
the existing job_id (logs `[compile] dedup hit — reusing job <id>`).
- `_purge_expired_jobs` evicts both COMPILE_JOBS and JOB_BY_KEY,
keeping the index consistent. Edge case where two jobs share a key
(old finished, new running) is handled — only evict the key entry
if it still points at the purged job.
2. Concurrency control (`backend/app/api/routes/compile.py`)
- `_COMPILE_SEMAPHORE = asyncio.Semaphore(2)` global cap on
simultaneous compiles.
- `_target_lock(board_fqbn)` returns a per-target asyncio.Lock so
concurrent compiles to the SAME board (sharing the persistent build
dir) serialise. Different boards still run in parallel up to the
semaphore cap.
- `_compile_job` acquires sema → per-target lock → flips state to
`running` → calls `_run_compile`. Pending state now accurately
reflects "queued waiting for resources".
3. Persistent build dir (`backend/app/services/espidf_compiler.py`)
- New `_prepare_persistent_project_dir(idf_target)` materialises
`/var/lib/velxio-build/<target>/project/` from the template on
first use; on subsequent compiles it wipes only `main/` and
`user_libs/` (the per-compile parts) and leaves `build/` alone so
ninja's incremental cache + ccache .o files survive.
- Toolchain version sentinel (`.idf_version`) wipes the whole target
dir if the ESP-IDF or arduino-esp32 version changes — cached
objects from the old toolchain are no longer ABI-compatible.
- `compile()` is now a thin dispatcher: persistent path or fallback
to the legacy `tempfile.TemporaryDirectory()` flow. The actual
build logic was extracted into `_compile_in_dir()` so both paths
share one implementation, no duplication.
- Escape hatch: `VELXIO_PERSISTENT_BUILD_DIR=0` env var falls back
to the tempfile path without rebuilding the image. Critical for
production safety.
4. ccache normalisation (`Dockerfile.standalone`)
- + `ENV CCACHE_BASEDIR=/var/lib/velxio-build` makes ccache canonicalise
absolute paths under that prefix when computing the cache key.
Robustens hits against any future subdir rearrangement.
5. Docker compose (`docker-compose.yml`)
- + named volume `velxio-build:/var/lib/velxio-build` so the persistent
build dir survives `docker compose up -d --build`.
- + env `VELXIO_PERSISTENT_BUILD_DIR=1` (default ON; users disable
without rebuilding).
Expected impact
- Cold first compile per container per target: unchanged (~5-7 min).
- Same sketch re-compiled: ~2-5 s (everything cached).
- Different sketch, same target: ~5-30 s (only user code + new lib steps
rebuild; ESP-IDF base hits cache).
- Different sketch with new libraries: ~30-90 s (new lib component
compiles; rest hits cache).
- Concurrent clicks on same example: 1 build, others poll the same
job_id. No more six-ninja meltdown.
Tests
- `test/backend/unit/test_compile_dedup.py` covers `_job_key` stability +
variance and `_purge_expired_jobs` consistency (including the
"two jobs share a key" edge case).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The synchronous /api/compile endpoint forced one long-lived HTTP request
to span the entire build. Cloudflare's 100s edge timeout cuts that off
mid-flight for any cold ESP-IDF compile (BMP280 takes 5-7 min on first
run). The user-visible symptom was HTTP 524 well before the backend
even noticed.
Backend (compile.py)
- New `POST /api/compile/start` returns `{job_id}` immediately and
spawns the actual compile as an asyncio.create_task background.
- New `GET /api/compile/status/{job_id}` returns the current job state
(`pending` | `running` | `done` | `error`). Each poll completes in
milliseconds, far under any edge timeout.
- Existing `POST /api/compile/` kept verbatim for backward compatibility
(AVR/RP2040 builds finish in seconds and don't trip 524).
- Build logic extracted into `_run_compile()` so both paths share one
implementation; no duplicated ESP-IDF / arduino-cli branching.
- Async path opens its own short-lived DB session via AsyncSessionLocal
for metric recording — the request-scoped session is dead by the time
the background task finishes.
- COMPILE_JOBS dict purges entries 30 minutes after completion so a
busy server doesn't grow unboundedly.
Frontend (compilation.ts)
- compileCode() now: POST /compile/start → poll /compile/status every 2s
until state ∈ {done, error}, with a 15-minute client-side cap.
- 30s axios timeout per individual call (not per build) so transient
network blips during a long compile auto-retry instead of failing.
- 404 on /status throws (job expired / server restarted); other poll
errors warn and retry. Surfaces structured error responses verbatim
so the editor's compile-error panel keeps working unchanged.
Limitation: COMPILE_JOBS lives in-process; if velxio ever scales to
multiple FastAPI workers this needs to move to Redis or sqlite. Single-
instance is fine today.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
First open-source end-to-end emulation of the AI-Thinker ESP32-CAM
in QEMU, paired with a browser webcam → firmware bridge so users can
develop camera sketches without hardware. Status: esp_camera_init()
returns ESP_OK; OV2640 chip-id verifies (PID/VER/MIDH/MIDL exactly
match the datasheet); GPIO 25 VSYNC NEGEDGE interrupt enabled by
the upstream driver. Final piece (cam_task accepting frames) is in
progress — descriptor walker fix landed in this commit.
Backend (Python/FastAPI):
- simulation.py: camera_attach/frame/detach WS handlers
- esp32_worker.py: ctypes binding to velxio_push_camera_frame +
feature-detection fallback for older DLLs
- esp32_lib_manager.py: forward camera commands to the worker stdin
- esp-idf-template/main/CMakeLists.txt: esp32-camera headers added
via add_prebuilt_library + REQUIRES driver (resolves i2c_master_*
symbols). LED_BUILTIN=2 fallback for sketches that hardcode it.
Frontend (React/TS):
- EditorToolbar.tsx: ESP32-CAM (and the rest of the ESP32 family)
added to isQemuBoard list — Run button now starts the QEMU bridge
for these boards instead of falling through to the AVR path
- useWebcamFrames.ts: getUserMedia → OffscreenCanvas →
toBlob('image/jpeg') → base64 → WS at ~10 fps
- CameraToggle.tsx: header button with status colors + frame counter
- SimulatorCanvas.tsx: render CameraToggle for esp32-cam boards
- Esp32Bridge.ts: sendCameraAttach/Frame/Detach + chunked btoa
- useSimulatorStore.ts: diagnostic log on compileBoardProgram
- components-metadata.json: regen including esp32-cam component
Submodule pointer:
- wokwi-libs/qemu-lcgamboa → ff8eee0 (camera devices commit on
davidmonterocrespo24/qemu-lcgamboa branch picsimlab-esp32)
Investigation + tests in test/test-esp32-cam/:
- 13 autosearch markdown docs (overview, SOTA, OV2640 spec, DVP/I2S
spec, build blueprint, blockers resolved, descriptor walker fix)
- 5 sketches (camera_init, sccb_probe, dma_smoke, frame_roundtrip,
webcam_demo) + 8 live + WS regression tests
- README with the user-facing flow
.gitignore:
- libqemu-*.dll.{pre-camera,new,bak} (rollback points, regenerated)
- wokwi-libs/esp32-camera/ (clone consumed by arduino-esp32 path,
not part of this repo)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Backend:
- Add version field to InstallLibraryRequest
- Add fallback and requested_version to InstallResponse
- Add DELETE /api/libraries/uninstall endpoint
- Enhance install_library() for versioned installs (LibName@version)
- Add semver validation and fallback logic
- Add uninstall_library() method
- Fix _parse_version() to reject non-numeric version parts
Frontend:
- Update installLibrary() with optional version parameter
- Add uninstallLibrary() and resolveLibraryVersion() helpers
- Add version selector dropdown in Library Manager
- Add UNINSTALL button for installed libraries
- Show fallback messages when requested version unavailable
- Add parseLibSpec() and version badges in InstallLibrariesModal
The project save/load pipeline only persisted a single `board_type`, so
multi-board workspaces silently lost every board except the active one
on save, and wires referencing the dropped boards' IDs orphaned to the
canvas corner on reload. An audit of the production backup found 74/306
projects (24%) with at least one orphaned wire and 174/301 non-trivial
projects whose code was still the default Blink template — strong signal
that users save once and never re-save.
Backend
- Add `boards_json` column on `projects` with idempotent ALTER TABLE in
the lifespan migration list.
- New `FileGroup` schema + `file_groups` array on
ProjectCreate/Update/Response. Legacy `files`/`code` kept for back-compat.
- `project_files.py` now uses `{pid}/{groupId}/{filename}` subdirs via
`read_groups`/`write_groups`. Legacy flat layouts are auto-promoted on
read; legacy single-list `files` only updates the active group, leaving
other boards' files intact.
- `_persist_files_from_body` honors file_groups → files → code priority.
Frontend
- `useSimulatorStore.addBoard` accepts an optional `explicitId` so
saved board IDs can be restored verbatim (wires reference IDs literally).
- New `loadProjectState({boards, fileGroups, components, wires,
activeBoardId})` action: tears down current boards, recreates from the
payload, restores file groups atomically, recalculates wire positions
on the next frame, and refreshes the Interconnect.
- `useEditorStore.replaceFileGroups` for atomic multi-group restore.
- `SaveProjectModal` and `ProjectByIdPage`/`ProjectPage` now go through
`buildSavePayload` / `buildLoadPayload` (handles pre-backfill projects
by synthesising a default board from `board_type`).
Auto-save (#useAutoSaveProject hook)
- 2.5s debounced silent PUT triggered ONLY when an authenticated user
has a `currentProject` with a UUID. State hash detects real changes
vs. UI-only churn; baseline is reset on project load so the just-loaded
state isn't immediately re-saved.
- `beforeunload` flush via `fetch keepalive: true` (supports PUT +
credentials, survives unload).
- Compact status indicator in `AppHeader` (idle/dirty/saving/saved/error).
Backfill script (one-off, idempotent)
- `backend/scripts/backfill_boards_2026_05.py` populates `boards_json`
for legacy projects. Heuristic per project, based on which board IDs
the wires reference:
Case A — wires only ref 'arduino-uno' but board_type ≠ uno:
rename id→board_type and rewrite wire endpoints.
Case B — single-board normal: keep verbatim.
Case C — multi-board: recreate one board per distinct ref, infer
kind by stripping trailing -N suffix.
Also moves any flat files into the active board's group subdir.
Stdlib-only, runs from host or `docker exec`.
Docker
- `Dockerfile.standalone` now copies `backend/scripts/` into the image
so the backfill is callable via `docker exec velxio-app python
/app/scripts/backfill_boards_2026_05.py --apply`.
Verified locally on the restored production backup (363 projects):
33 Case A, 316 Case B, 14 Case C, 135 wire endpoints renamed, 0 orphans.
Re-running the script after apply skips all 363 (idempotent).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- Introduced SVG layout dimensions for Phase 1 (B/W mono) and Phase 2 (colour) ePaper panels, detailing active areas, bezels, and pin layouts.
- Developed a phased emulation plan outlining the architecture and deliverables for different panel types, including SSD168x and UC81xx.
- Created a canonical "Hello, World!" sketch for the 1.54" ePaper panel, ensuring compatibility across ESP32, Raspberry Pi Pico, and Arduino Uno.
- Implemented a pure Python SSD168x decoder to validate SPI command sets and framebuffers against specifications.
- Added tests for compiling the hello-world sketch across supported boards and for the SSD168x protocol to ensure correct framebuffer behavior.
- Implemented `esp32_spi_chip_demo.ino` to demonstrate SPI communication with a 74HC595 shift register.
- Created `esp32_uart_chip_demo.ino` for UART loopback testing with ROT13 transformation.
- Added Python tests for compiling chips and sketches, ensuring valid WASM output and successful compilation for various board families.
- Developed end-to-end tests for ESP32 with custom chips using I2C and SPI, validating synchronous communication through the backend.
- Introduced GPIO bridge tests to verify serial communication and GPIO state changes.
- Ensured all tests validate the expected behavior of the custom chips and their interaction with the ESP32 firmware.
Track per-user, per-project, and per-board usage to inform pricing tier
decisions. Adds an admin dashboard with KPIs (DAU/WAU/MAU, totals,
success rate), time-series charts for compiles/runs, board family +
FQBN breakdowns, "board diversity" pie chart (key freemium signal),
top users/projects, and per-country breakdown via Cloudflare's
CF-IPCountry header. Admin can now also view private projects.
Backend:
- New UsageEvent table (append-only event log with user_id, project_id,
event_type, board_fqbn/family, country, error_kind, duration_ms)
- Aggregate counters on User (total_compiles/runs/errors, last_active,
signup_country, last_country) and Project (compile/run/update counts,
last_compiled/run timestamps) kept in sync by MetricsService for O(1)
dashboard reads
- 10 admin endpoints under /api/admin/metrics/{overview, timeseries,
boards, board-diversity, top-users, top-projects, countries,
users/{id}, projects/{id}}
- POST /api/metrics/run for client-side run telemetry
- Country detection via cf-ipcountry header (no DB / no API calls)
- Auto-migrations in lifespan for legacy DBs
Frontend:
- recharts-powered Dashboard tab with KPI cards and 4 charts
- New Boards tab with per-family + per-FQBN breakdown
- Country column with flag emoji on Users tab
- Top countries card on Dashboard
- compileCode now forwards project_id; Run button reports via WS
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
- Implement `ammeter-waveform.test.ts` to validate AC readings from a sine wave source.
- Create `capacitor-charge-transient.test.ts` to test the charging response of an RC circuit driven by a microcontroller pin.
- Introduce `esp32-rectifier-integration.test.ts` for testing rectifier behavior using QEMU and ESP32.
- Add helper functions in `esp32RectifierE2E.ts` for the rectifier test harness.
- Develop `voltmeter-waveform.test.ts` to ensure correct AC and DC readings from a sine wave source.
- Implement unit tests for waveform statistics in `waveform-stats.test.ts` to validate RMS, mean, peak, and interpolation functions.
- Create `waveformStats.ts` to provide statistical functions for time-domain waveform analysis.
Frontend WiFi detection via file-content scanning was unreliable because
fileGroups[board.activeFileGroupId] could be an empty array (not null),
bypassing the ?? fallback to editorState.files.
Fix: the ESP-IDF compiler now returns has_wifi:bool in its compile response.
The frontend stores this on the BoardInstance and uses it in startBoard()
instead of scanning file contents. The file-content scan is kept as a
fallback for boards that haven't been compiled in this session.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Replace arduino-cli with ESP-IDF 4.4.7 for ESP32 compilation — Arduino-compiled
firmware crashes in QEMU (9-28 reboots) while ESP-IDF boots cleanly (0 reboots).
The new espidf_compiler translates Arduino WiFi/WebServer sketches to native
ESP-IDF C code, compiles with cmake+ninja, and merges into 4MB flash images.
Key changes:
- ESP-IDF compiler: translates WiFi.begin/WebServer to esp_wifi/esp_http_server
- ESP-IDF project template with QEMU-optimized sdkconfig (DIO, 40MHz, no WDT)
- WiFi status parser for ESP-IDF serial logs (wifi_status, ble_status events)
- IoT Gateway HTTP reverse proxy for ESP32 web servers
- WiFi/BLE auto-detection from sketch content + visual status icons
- Static IP 192.168.4.15 matching slirp DHCP first-client range
- Docker: new espidf-builder stage with ESP-IDF 4.4.7 toolchain
- 157 tests covering WiFi/BLE for both ESP32 (Xtensa) and ESP32-C3 (RISC-V)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Added board-agnostic sensor registration methods in RP2040Simulator.
- Enhanced ComplexParts to handle LEDC PWM duty updates for ESP32.
- Updated ProtocolParts to check if the simulator handles sensor protocols natively, delegating to backend if applicable.
- Introduced pre-registration of sensors in useSimulatorStore for ESP32 to prevent race conditions.
- Added tests for ESP32 DHT22 sensor registration flow, ensuring proper delegation and fallback mechanisms.
- Created tests for ESP32 Servo and Potentiometer interactions, verifying PWM subscriptions and ADC handling.
- Updated components-metadata.json with new generated timestamp.
- Refactored Esp32C3Simulator.ts to remove unnecessary debug variables and logging, and added support for additional ROM functions.
- Modified useSimulatorStore.ts to clarify bridge usage for ESP32 boards.
- Updated submodules for QEMU and other libraries to indicate dirty state.
- Added test_esp32c3_emulation.py for end-to-end testing of ESP32-C3 emulation, including compilation, flash image merging, and GPIO event checking.
- Added detailed logging for GPIO changes, system events, and errors in simulation websocket.
- Improved ESP32 firmware handling by merging individual binaries into a single 4MB flash image.
- Updated ESP32 bridge to handle serial output and GPIO changes with appropriate logging.
- Introduced integration test for ESP32 emulation, covering compilation, WebSocket connection, and event handling.
- Enhanced examples to include ESP32 projects and updated the examples gallery to reflect new board types.
- Refactored simulator store to manage ESP32 bridge and simulator instances more effectively.
- Updated requirements to include esptool for ESP32 firmware management.
- Added ESP32 emulation plan and architecture documentation.
- Created `esp_qemu_manager.py` for managing ESP32 QEMU instances.
- Modified backend API routes to support ESP32 firmware loading and GPIO handling.
- Introduced `Esp32Bridge.ts` for frontend communication with ESP32 instances.
- Refactored simulator store to support multiple boards, including Raspberry Pi and Arduino.
- Created `RaspberryPi3Bridge.ts` for WebSocket communication between frontend and backend for Raspberry Pi.
- Updated QEMU manager to handle multiple serial ports for Raspberry Pi GPIO communication.
- Enhanced SimulatorCanvas to render multiple boards and manage wire routing between them.
- Implemented board picker modal for selecting and adding boards to the canvas.
- Updated editor to support multiple file groups per board.
- Added migration logic for loading old project formats into the new multi-board structure.
- Ensured backward compatibility with existing components and functionality.
- Introduced new BoardKind types for Raspberry Pi 3B and updated BoardInstance interface.
- Added BOARD_KIND_LABELS and BOARD_KIND_FQBN mappings for new board types.
- Implemented physical to BCM GPIO mapping for Raspberry Pi 3B in boardPinMapping utility.
- Updated BOARD_COMPONENT_IDS to include Raspberry Pi 3B.
- Enhanced isBoardComponent function to support new board type.
- Modified boardPinToNumber function to handle pin mapping for Raspberry Pi 3B.
- Created a new DocsPage component for project documentation with links to GitHub and Discord.
- Added Arduino sketch for serial communication test between Raspberry Pi and Arduino.
- Implemented avr_runner.js to emulate ATmega328P and bridge serial communication over TCP.
- Developed a Python test script to validate the serial integration between the emulated Raspberry Pi and Arduino.
- Implemented `require_admin` dependency to enforce admin access control.
- Added `is_admin` column to the users table for role management.
- Created admin routes and schemas for user and project management.
- Developed AdminPage with user and project management tabs.
- Integrated user editing and deletion functionalities in the admin panel.
- Added setup screen for creating the first admin user.
- Updated frontend to include admin functionalities and user role display.
- Generated Open Graph image for better social media integration.
- Google OAuth callback now redirects to /editor instead of landing page
- Landing page nav shows avatar, username and dropdown when logged in
(My Projects, Open Editor, Sign out)
- Skeleton placeholder during checkSession so login button never flickers
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- FRONTEND_URL and COOKIE_SECURE are now read from settings (env vars)
- Add COOKIE_SECURE config field (false by default, true in prod)
- backend/.env sets FRONTEND_URL=https://www.velxio.dev and COOKIE_SECURE=true
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Backend:
- project_files.py: read/write sketch files to /app/data/projects/{id}/
- GET /api/projects/{id}: load project by ID (public = anyone, private = owner only)
- create/update write files to disk volume; delete removes them
- ProjectResponse includes files[] list loaded from disk
Frontend:
- /project/:id canonical route -> ProjectByIdPage
- ProjectPage (legacy /:username/:slug) redirects to /project/:id after load
- SaveProjectModal sends files[] and navigates to /project/{id} after save
- DATA_DIR env var in both compose files
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Add LoginPage and RegisterPage for user authentication.
- Create UserProfilePage to display user projects.
- Implement ProjectPage for viewing and editing individual projects.
- Introduce authService for handling user login, registration, and session management.
- Add projectService for managing project data retrieval and manipulation.
- Enhance EditorPage with file management capabilities and save prompts.
- Introduce Zustand stores for managing authentication, editor state, and project state.
- Add reserved usernames utility to prevent certain usernames during registration.
- Update compilation service to handle multiple files for Arduino sketches.
- Simplified serial data handling in `useSimulatorStore` for both AVR and RP2040 simulators.
- Introduced `boardPinMapping.ts` to map wokwi-element pin names to simulator GPIO/pin numbers for Arduino Uno and Nano RP2040.
- Added `compilationLogger.ts` to parse compile results into structured log entries for better console output.
- Added SimulatorCanvas component for rendering the simulator interface.
- Integrated Wokwi components (Arduino, LED, Resistor, Pushbutton, Potentiometer) into the simulator.
- Created PinManager to handle pin state changes and notifications.
- Developed AVRSimulator class for emulating Arduino Uno functionality.
- Implemented hex file loading and compilation service.
- Added CSS styles for the simulator interface.
- Established Zustand stores for managing editor and simulator states.
- Created utility functions for parsing Intel HEX format.
- Set up Vite configuration for the frontend project.
- Added batch scripts for starting backend and frontend servers, and updating Wokwi libraries.
davidmonterocrespo24
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