- onPortMessage gains CREATE_DOWNLOAD_URL + REVOKE_DOWNLOAD_URL branches.
- handleCreateDownloadUrl helper decodes SW-supplied base64 archive bytes
via base64ToBlob, mints a blob:URL via URL.createObjectURL, and posts
DOWNLOAD_URL{requestId,url} back on the keepalivePort. On any failure
(empty payload, decode throw, mint throw) responds with url:'' so the
SW's outer timeout / typed error path fires cleanly.
- mintedDownloadUrls Set tracks minted URLs purely as a diagnostic signal;
unknown-URL revokes get a warn but still execute (WHATWG spec: revoke
on unknown URL is a no-op).
- base64ToBlob added to the existing src/shared/binary import.
- No changes to bootstrap/connectPort/ping/segment-rotation/__MOKOSH_UAT__
test hooks. Concurrent mints are allowed (URL minting is stateless
per-Blob); only encodeAndSendBuffer needs its existing in-flight guard.
Architectural rationale (D-P2-01): SW lacks URL.createObjectURL per
DEC-006; offscreen has it. Reusing the existing keepalivePort (D-17)
avoids two connect-overhead penalties per save flow.
Mark
f0b95f4a83