Convert Image, and HEIC opens because av-club already knew how

the fourth task. same shape as the other three — beside the original, skip an
existing output, skip a file already in the target format, delete only when asked
and only after the write.

/v1/sharp gets the same path mode /v1/ffmpeg got, for the same reason: the file
browser and the commander both already have the file.

HEIC IS THE POINT OF THIS ONE, and nothing in the task does anything about it.
`decodable.ts` has routed HEIC through ImageMagick since before I touched this
plugin, because the libheif inside sharp is built without the HEVC decoder — a
HEIC reads its own header fine and then fails on the pixels, which looks exactly
like a corrupt file and is not one. the task simply names `.heic` in its trigger
and asks. the photographs open.

I had diagnosed that gap independently against the file browser's thumbnails and
concluded a system decoder would be needed, twice telling the owner these files
could not be read. this plugin had already solved it and documented why. worth the
note: the answer was in the tree.

a path has no stored `format`, so sharp's `metadata()` supplies it — and that only
reads the header, which is precisely the part of a HEIC that works, so it correctly
identifies the files needing ImageMagick.

`rotate` with no argument is in every pipeline: it applies the EXIF orientation and
drops the tag. without it a portrait photo from a phone converts to a landscape
image that viewers rotate back, until one does not.

max_dimension shrinks to fit and never enlarges. quality 82 for jpeg and webp, 55
for avif — where a photograph stops looking better and only gets bigger.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tasks/convert-image/TASK.md

@@ -0,0 +1,52 @@
+---
+name: Convert Image
+description: Convert photos between formats through av-club — including HEIC from a phone, which most tools cannot read. Optionally shrink to fit a maximum size.
+category: Image
+version: 1
+mode: script
+language: typescript
+inline: ask
+args:
+  - file_path
+inputs:
+  file_path:
+    type: string
+    description: An image, or a folder to convert recursively.
+  target_format:
+    type: string
+    default: jpeg
+    options: [jpeg, png, webp, avif, tiff]
+    description: Format to convert to.
+  max_dimension:
+    type: string
+    default: original
+    options: [original, "3000", "2000", "1600", "1200", "800"]
+    description: Shrink so neither side exceeds this, keeping the aspect ratio. Never enlarges.
+  delete_source:
+    type: boolean
+    default: false
+    description: Delete each source file once its conversion has been written.
+trigger:
+  - type: file
+    extensions: [heic, heif, jpg, jpeg, png, webp, avif, tif, tiff, gif, bmp, jp2]
+  - type: directory
+---
+
+# Convert Image
+
+Writes the result **beside the original** — `IMG_3707.HEIC` becomes `IMG_3707.jpeg` in the same folder.
+
+**HEIC works here**, which is worth saying because it does not work in most places. Every photo a
+recent iPhone takes is HEVC-coded HEIF, and the libheif that ships inside sharp is built without the
+decoder for it — so a HEIC reads its own header fine and then fails on the pixels, looking exactly
+like a corrupt file. av-club routes those through ImageMagick, which links the system libheif and can
+decode them, and hands sharp a lossless PNG. You do not have to know any of that; it just opens.
+
+`max_dimension` shrinks so neither side is larger than the number, keeping the aspect ratio, and never
+enlarges a small image. Leave it on `original` to convert without resizing.
+
+Skips a file already in the target format, and never overwrites an existing output.
+
+Quality is 82 for jpeg and webp and 55 for avif — the point where a photograph stops getting visibly
+better and only gets bigger. EXIF orientation is applied, so a photo taken sideways comes out upright
+rather than rotated.