Module process 

Sniff, decode and derive the two files an attachment needs besides its original: a small thumbnail for the composer and transcript, and the “send-copy” the agent actually receives. SPEC_AGENT_PANE_IMAGE_ATTACHMENTS_2026_09_26.md §6.4.

Everything here is synchronous and CPU-bound; callers run it on a blocking thread.

Structs

Derived

Everything the pipeline derives from one original.

Encoded

One derived file, encoded in memory.

ProcessError

Why an image couldn’t be processed. code values are the AttachmentFailedEvent::code vocabulary.

Enums

Sniffed

What the first bytes of a file say it is. Extensions lie (a HEIC saved as .jpg is common), so every decision below goes through this.

Constants

MAX_PIXELS

Largest pixel count accepted before decoding.

MAX_SIDE

Largest side accepted before decoding (decompression-bomb guard).

SEND_MAX_BYTES

Upper bound on the send-copy’s size. Bedrock and Vertex cap images at 5 MB; the Anthropic API itself at 10 MB base64.

THUMB_EDGE

Long edge of the thumbnail.

Functions

check_dimensions

decode_cost_bytes

Bytes of memory a decode of a w×h image is budgeted at: the RGBA8 frame plus one working copy (a resize or colour conversion).

derive

Decode path (already sniffed as format) and produce the thumbnail and the send-copy. send_max_edge is the send-copy’s long edge.

encode_jpeg 🔒

encode_png 🔒

encode_send_copy 🔒

encode_thumbnail 🔒

ext_of

fit 🔒

gif_is_animated 🔒

has_real_alpha 🔒

True when some pixel is not fully opaque. Many screenshots carry an alpha channel that is 255 everywhere; those can still become JPEG.

header_dimensions

Width and height from the file header, without decoding pixels. Fails with too_large_dimensions past the bomb guard.

mime_of

sniff