docs(audit): state the packaged image read allowance

Packaged ELF, Mach-O and PE images are read in full and copied to a
temporary file, sharing one max_file_bytes allowance, but the docs and
coverage.allowances still said only a PE gets more than a header read.

Name the allowance and the copies in docs/release-exposure.md,
RELEASE_EXPOSURE_ALLOWANCES and the max_file_bytes description.

docs/release-exposure.md

@@ -46,7 +46,7 @@ The audit composes existing readers. It does not reread Electron fuse bytes itse
 
 `native.hardening`, `macho.hardened_runtime`, and `android.manifest` stay `not_assessed`. Their next probes are `inspect_binary_hardening`, `inspect_signature`, and `inspect_android_package`.
 
-Source map text is counted and then dropped. A selected file is read through the stable artifact reader. Text and source-map members stay inside the allowances listed under `coverage.allowances`, and each kind has its own allowance, so binary members cannot use up the read that a later source map needs. Native images on disk are registered from inventory classification and are not limited to those allowances. Other files and package members are identified from a bounded header. A header with no NUL byte, or one that starts with a UTF-16 byte order mark, is scanned as text, so names such as `.env.production`, `server.key`, and `credentials` do not depend on an extension list. UTF-16 without a byte order mark has NUL bytes and is not recognized this way. A member already known to be text, such as a script, is also scanned when it is UTF-8 holding a stray NUL. One whose header is at least an eighth NUL bytes is taken to be wide text. It is not decoded and is counted as skipped, as is UTF-32. A binary plist is decoded, so its strings, dictionary keys and data are scanned in whichever encoding each object uses. One that cannot be decoded still has its bytes scanned and is counted as skipped. A file whose header could not be read leaves `text.credential_markers` undecided. Among binary package members, only a PE is read further, for its debug records. A script that an HTML file loads is examined as a script whatever it is called, and an HTML file loaded this way is still examined as HTML. One read before that HTML file, one that is not found, one at a location the audit cannot place, or one past the 1 MiB of resolved script paths the audit keeps (`MAX_RELEASE_EXPOSURE_SCRIPT_TARGET_BYTES`) leaves `javascript.source_map_sources` undecided. Skipped members are listed under `coverage.omitted`. When the selection is a file, the parent directory is listed up to a fixed entry allowance for sibling `.pdb`, `.dSYM`, `.debug`, and linker `.map` debug companions.
+Source map text is counted and then dropped. A selected file is read through the stable artifact reader. Text and source-map members stay inside the allowances listed under `coverage.allowances`, and each kind has its own allowance, so binary members cannot use up the read that a later source map needs. Native images on disk are registered from inventory classification and are not limited to those allowances. Other files and package members are identified from a bounded header. A header with no NUL byte, or one that starts with a UTF-16 byte order mark, is scanned as text, so names such as `.env.production`, `server.key`, and `credentials` do not depend on an extension list. UTF-16 without a byte order mark has NUL bytes and is not recognized this way. A member already known to be text, such as a script, is also scanned when it is UTF-8 holding a stray NUL. One whose header is at least an eighth NUL bytes is taken to be wide text. It is not decoded and is counted as skipped, as is UTF-32. A binary plist is decoded, so its strings, dictionary keys and data are scanned in whichever encoding each object uses. One that cannot be decoded still has its bytes scanned and is counted as skipped. A file whose header could not be read leaves `text.credential_markers` undecided. A packaged ELF, Mach-O, or PE image is read in full and written to a temporary copy, removed afterward, so it can be probed for an embedded package. All packaged images share one `max_file_bytes` allowance. An image that does not fit is not probed and leaves member coverage `unknown`. A packaged PE is also read for its debug records. A script that an HTML file loads is examined as a script whatever it is called, and an HTML file loaded this way is still examined as HTML. One read before that HTML file, one that is not found, one at a location the audit cannot place, or one past the 1 MiB of resolved script paths the audit keeps (`MAX_RELEASE_EXPOSURE_SCRIPT_TARGET_BYTES`) leaves `javascript.source_map_sources` undecided. Skipped members are listed under `coverage.omitted`. When the selection is a file, the parent directory is listed up to a fixed entry allowance for sibling `.pdb`, `.dSYM`, `.debug`, and linker `.map` debug companions.
 
 Inventory stops at 65,536 entries or 2 GiB of hashed bytes, and member coverage then stays `unknown`. A declared integrity value that disagrees with the bytes does not stop the audit, because signing an unpacked native module after packaging is routine. The contradiction is recorded in the limitations and the audit continues.
 

src/domain/releaseExposure.ts

@@ -48,6 +48,7 @@ export const RELEASE_EXPOSURE_ALLOWANCES = [
   `Local source map targets keep at most ${String(MAX_RELEASE_EXPOSURE_MAP_TARGET_BYTES)} bytes of resolved paths. Later targets stay unassessed.`,
   `Source map scans read at most ${String(MAX_RELEASE_EXPOSURE_SOURCE_MAPS)} maps and ${String(MAX_RELEASE_EXPOSURE_SOURCE_MAP_BYTES)} bytes each. sourcesContent text is counted and then dropped.`,
   `Other files and package members are identified from their first ${String(MAX_RELEASE_EXPOSURE_MEMBER_PROBE_BYTES)} bytes, and those without a NUL byte in that prefix are scanned as text. Up to ${String(MAX_RELEASE_EXPOSURE_PACKAGED_PE_READS)} packaged PE images are read for debug records, ${String(MAX_RELEASE_EXPOSURE_PACKAGED_PE_BYTES)} bytes each.`,
+  "Packaged ELF, Mach-O, and PE images are read in full and copied to a temporary file to probe for an embedded package. They share one max_file_bytes allowance, and an image that does not fit is not probed.",
   `Go, Rust, and Electron fuse readers run on at most ${String(MAX_RELEASE_EXPOSURE_NATIVE_IMAGES)} native images.`,
 ] as const;
 
@@ -307,7 +308,7 @@ export const auditReleaseExposureInputSchema = z.strictObject({
     .max(MAX_RELEASE_EXPOSURE_FILE_BYTES)
     .default(MAX_RELEASE_EXPOSURE_FILE_BYTES)
     .describe(
-      "Selected-file and on-disk PE read ceiling. Text, source-map, and package members use the smaller allowances in coverage.allowances.",
+      "Selected-file, on-disk PE, and shared packaged-image read ceiling. Text, source-map, and other package members use the smaller allowances in coverage.allowances.",
     ),
 });