Reference

This page covers the technical details behind CodeComfy — what the limits are, how the pipeline works, what to do when things go wrong, and what the extension does (and does not) touch on your system.

Generation limits

Video generation enforces safety limits to prevent accidental resource exhaustion on your ComfyUI server and local disk.

Parameter	Minimum	Maximum
Duration	1 second	15 seconds
Frames per second	1	60
Total frames (duration x fps)	—	450

If you hit a limit, reduce the duration or choose a preset with a lower frame rate. Image generation does not have these constraints — it produces a single frame.

Prompt and seed constraints

• Prompts must be non-empty and no longer than 8,000 characters.
• Seeds must be whole numbers between 0 and 2,147,483,647.
• Only one generation can run at a time. A 2-second cooldown separates consecutive jobs.

How it works

The extension follows a linear pipeline from prompt to finished output.

Command Palette
    |
    v
extension.ts --- validates inputs, creates JobRouter
    |
    v
JobRouter --- creates run folder, tracks lifecycle
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    v
ComfyServerEngine --- POST /prompt -> poll /history -> stream /view
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    v
FFmpeg --- (video only) assemble frames into MP4
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    v
.codecomfy/outputs/index.json --- atomic index update

Step by step

1. Input validation. The extension checks that the prompt is non-empty and within length limits, the seed is valid (or generates a random one), and the ComfyUI server is reachable.
2. Job submission. A JSON workflow payload is POSTed to ComfyUI’s /prompt endpoint. The workflow is selected from built-in presets based on whether you chose image or video generation.
3. Polling. The extension polls /history/{prompt_id} to track progress. The VS Code status bar updates in real time (queued, generating, done, error).
4. Download. When ComfyUI reports the job is complete, the extension downloads the output files via the /view endpoint. For video, this means downloading every individual frame.
5. Assembly (video only). FFmpeg takes the downloaded frames and assembles them into an MP4 file. The frame images are kept alongside the video.
6. Index update. The output index at .codecomfy/outputs/index.json is updated atomically so that gallery tools can discover completed runs.

Troubleshooting

Error messages from CodeComfy are prefixed with a category tag to help you narrow down the problem area quickly.

[Network] — Cannot reach ComfyUI server

The extension could not connect to the configured ComfyUI URL.

• Is ComfyUI running? Open http://127.0.0.1:8188/system_stats in a browser. If you see JSON output, the server is up.
• Wrong URL or port? If ComfyUI runs on a non-default port or a remote host, update codecomfy.comfyuiUrl in your settings.
• Firewall or proxy? Try curl http://127.0.0.1:8188/system_stats from a terminal. If curl fails too, the problem is at the network level, not in the extension.

[Server] — ComfyUI returned an error

The extension reached ComfyUI, but the server rejected the request or failed during execution.

• Check the ComfyUI terminal or console output for Python stack traces.
• The most common cause is a missing model checkpoint or a custom node that is not installed.
• Make sure your ComfyUI installation has all the nodes required by the preset workflow.

[API] — Unexpected response shape

The extension received a response from the ComfyUI URL, but the JSON structure did not match what it expected.

• Your ComfyUI version may be too old or too new for the bundled presets. Try updating ComfyUI.
• A reverse proxy, CDN, or authentication layer between the extension and ComfyUI may be modifying responses. Hit /prompt and /history directly in a browser to inspect the raw JSON.

[IO] — File permission or disk issues

The extension could not write outputs to the workspace.

• Make sure the workspace folder is writable by your user account.
• Check available disk space — frame downloads for video can be large.
• On Windows, workspaces on network drives may have performance or permission issues. Use a local drive for best results.

FFmpeg not found

Video generation requires FFmpeg but the extension could not locate it.

• Install FFmpeg and make sure ffmpeg (or ffmpeg.exe on Windows) is on your system PATH.
• Alternatively, set codecomfy.ffmpegPath to the full absolute path, for example C:\ffmpeg\bin\ffmpeg.exe.
• Relative paths and bare names (other than PATH-resolved ffmpeg) are rejected for security — the extension needs to know exactly which binary it is executing.

”Generation already running”

Only one generation runs at a time. Cancel the current job first (CodeComfy: Cancel Generation in the Command Palette) or wait for it to finish. A 2-second cooldown applies between consecutive jobs.

Known limitations by platform

Platform	Status
Windows 10/11	Fully tested. Primary development platform. All features work.
macOS	Image and video generation are expected to work. NextGallery auto-detection is not available — set codecomfy.nextGalleryPath manually if needed.
Linux	Same as macOS: core generation works, NextGallery needs a manual path.
Remote / WSL	Works as long as the ComfyUI URL is reachable from the machine running VS Code. If VS Code is local and ComfyUI is in WSL, use the WSL IP or localhost forwarding.

The core pipeline (prompt submission, polling, download, FFmpeg assembly) is platform-agnostic. The only Windows-specific behavior is NextGallery auto-detection, which falls back gracefully to a settings prompt on other platforms.

If you encounter a platform-specific issue, open an issue with your OS, VS Code version, and ComfyUI version.

Security scope

CodeComfy is conservative about what it touches on your system.

• Network: the extension connects only to the user-configured ComfyUI URL (default http://127.0.0.1:8188). No other outbound HTTP requests are made. No telemetry, no analytics, no phone-home.
• Filesystem: outputs are written exclusively to .codecomfy/outputs/ and .codecomfy/runs/ inside the workspace. The extension does not read or write files outside the workspace.
• FFmpeg execution: all FFmpeg spawns use the non-shell execution path (shell: false). The FFmpeg path must be an absolute, existing, executable file — no relative paths or bare names are accepted (except the system PATH lookup fallback).
• No telemetry of any kind is collected or transmitted. See SECURITY.md for the full policy.