fix: comfy download copies on-disk local outputs instead of refusing them (BE-2190)

[mattmillerai]

ELI-5

If you run a workflow locally and then try to comfy download its result, ComfyUI already wrote the image to your disk — there's no web address to fetch. But download is a web-fetcher with a safety guard that refuses anything that isn't an http(s):// link, so it choked on the plain file path with refusing to download from non-HTTP URL: /…/output/foo.png. This teaches download to notice "hey, that's already a file on disk" and just copy it into your output folder instead of trying to fetch it — while keeping the safety guard fully in force for real remote URLs.

What & why

Fixes #480.

A comfy run --where local --wait job records bare absolute output paths (run/execution.py::format_image_path returns an on-disk path for loopback hosts). comfy download fed those through _assert_download_url, whose anti-SSRF guard rejects any non-http(s) URL → [download_failed]: refusing to download from non-HTTP URL.

The fix (additive — SSRF guard untouched for real URLs)

• New _local_source_path(url) returns a Path for a bare absolute filesystem path or a file:// URL with no remote host, and None for anything carrying a network scheme (http/https/ftp/gopher/data/…). A file:// URL pointing at a remote host returns None too, so it still hits the guard.
• In the download loop: when the source is local, shutil.copyfile it into --out-dir (no HTTP request, so the SSRF guard is irrelevant — there is no host to forge a request to). Everything else still runs through _assert_download_url exactly as before.
• Extension fix (latent bug called out in comfy download refuses local runs: "refusing to download from non-HTTP URL" for on-disk output paths from comfy run --where local --wait #480): a bare path has no ?filename= query param, so the old code mislabeled every local output .png. The copied file now takes its extension from the real source file.
• The destination-symlink refusal now runs for both branches (copy and fetch); a missing local source produces a clean download_failed envelope, not a traceback.

Acceptance criteria

1. ✅ comfy download <prompt_id> --where local succeeds for an on-disk output, copying it into --out-dir and returning its path.
2. ✅ _assert_download_url still rejects non-http(s) URLs on the remote/download path — tests cover both the local-copy branch and a rejected non-http URL (ftp://, remote-host file://, gopher://, data:) end-to-end through the loop.
3. ✅ Copied local outputs keep their real extension (.webp, .mp4, …), not hardcoded .png.

Testing

• Added TestLocalOutputCopy (bare path copy, extension preservation, file:// URI, missing-source error) and TestSSRFGuardIntact (guard still rejects non-http; remote-host file:// not treated as local; non-http rejected end-to-end through the loop).
• pytest tests/comfy_cli/command/ → 1066 passed, 1 skipped.
• ruff check + ruff format --check clean.

Judgment calls

• Local detection uses Path(url).is_absolute() (platform-aware for POSIX /… and Windows C:\…) after ruling out the file:// scheme. Network URLs are never absolute paths, so they always fall through to the SSRF guard. A protocol-relative //host/path would be treated as a local read (not a network fetch) and simply fail is_file() with a clean error — not an SSRF vector, and not a form the producer emits.
• The emitted files[].url for a local output is the bare source path (provenance); the transfer schema types url as an unconstrained string, so this validates.

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 78957fe3-a73c-406e-a858-4e85996f4a95

📥 Commits

Reviewing files that changed from the base of the PR and between a628223 and eb3d157.

📒 Files selected for processing (2)

• comfy_cli/command/transfer.py
• tests/comfy_cli/command/test_transfer_download.py

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch matt/be-2190-download-local-outputs

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch matt/be-2190-download-local-outputs

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[github-actions]

🔍 Cursor Review — Consolidated panel

Triggered by @mattmillerai.

Found 6 finding(s).

Severity	Count
🟠 High	2
🟡 Medium	2
🟢 Low	1
⚪ Nit	1

Panel: 8/8 reviewers contributed findings.