[davecraig]

MapLibre Native's PMTilesFileSource never removes an entry from its map of in-flight requests: not when a tile has been answered, and not when the request is cancelled, as it registers no onCancel. So every tile it reads leaves two file requests alive for good, each holding a mailbox whose queue keeps the first 4 KB block it allocated. On the test farm that showed up as the A54's native heap growing by tens of megabytes over two hours, nearly all of it held from mln::Mailbox::push. The same code is built for iOS.

• The style's offline source is now a soundscape-extract:// URL, served by OfflineExtractTiles, a MapResourceProvider on the default map runtime. It builds the TileJSON from the extract's header and metadata as PMTilesFileSource did, and reads and un-gzips tiles with PmTilesReader. Up to four extracts are kept open, one read at a time each; a file that has changed is opened again, and one that has gone is dropped.
• PmTilesReader also reads the header's zoom range, bounds and centre, and can return a tile already decompressed.
• Tiles served this way go into MapLibre's ambient cache, keyed by a URL naming the extract's path, which is now why each download still gets a unique filename. The comments saying so are updated.

Network tiles are unaffected: they don't go through PMTilesFileSource.