M8: a shared JBIG2 dictionary leaves with whatever used it, by any route

Redaction starts from the images a run replaces or removes and the forms
and soft masks under them, so a dictionary used by something that left
another way stays, with apply returning Ok: a stamp or widget appearance, a
Type 3 glyph, an /Alternates entry, a /Mask, or an image with /Filter by
reference or /DecodeParms through a reference to a reference. A
byte-identical copy stays too, which is what pdfseparate then pdfunite
leaves, and Remove Hidden Information never takes a dictionary out.

Compare what a full save would keep before and after the run instead, the
same walk write_full makes, now cos::reachable. What left names the
dictionaries, in any entry of its parameters; what stays that names one, or
a copy, is stored again without it; and the walk is taken once more, so a
dictionary still kept refuses the run, whatever keeps it. An image with
/Width, /Height or /Filter by reference is read, and is one bit in the copy,
as it was when drawn. /Alternates stays with what is stored again, and a
stream that isn't JBIG2 refuses rather than being stored.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AmsdeUCdTaD72jkDw2pJKY

parity/acrobat-features.toml

@@ -5829,8 +5829,8 @@ milestone = "M8"
 status = "shipped"
 commands = ["redact.apply"]
 tools = ["redact_apply"]
-evidence = ["crates/redact/src/tests.rs::images_are_removed_or_have_their_pixels_cleared", "crates/redact/src/tests.rs::redaction_clears_pixels_intersected_without_covering_their_centres", "crates/redact/src/tests.rs::a_fax_image_has_its_covered_pixels_cleared_instead_of_being_removed", "crates/redact/src/tests.rs::group_3_on_bytes_is_removed_whole_and_other_fax_images_cleared", "crates/redact/src/tests.rs::an_image_whose_predictor_is_given_by_reference_has_the_covered_pixel_cleared", "crates/redact/src/tests.rs::a_jbig2_image_has_its_covered_pixels_cleared_instead_of_being_removed", "crates/redact/src/tests.rs::a_jbig2_image_that_cannot_be_cleared_for_certain_is_removed_whole", "crates/redact/src/tests.rs::a_redacted_jbig2_scan_keeps_neither_its_code_nor_its_globals", "crates/redact/src/tests.rs::a_cleared_black_and_white_scan_is_stored_as_group_4", "crates/redact/src/tests.rs::globals_a_redacted_jbig2_image_shares_with_another_page_leave_the_file"]
-notes = "intersected pixel footprints are cleared conservatively in a copy, CCITT fax and JBIG2 images (scans stored as Group 4 or JBIG2, with their /JBIG2Globals) included; DCT/JPX images, Group 3 on bytes (which the bootstrap renderer may draw as other rows than the decoder reads), and a JBIG2 image whose page isn't its size, removed whole. The copy is Flate, or for a one-bit image of one component Group 4, or JBIG2 when it was JBIG2, whichever is smallest as stored, and refers to no globals; every other image using a redacted image's globals is stored again without them (Flate, Group 4 or JBIG2, whichever is smallest), so they leave the file (one that can't be decoded refuses the redaction)"
+evidence = ["crates/redact/src/tests.rs::images_are_removed_or_have_their_pixels_cleared", "crates/redact/src/tests.rs::a_redacted_scans_shared_jbig2_dictionary_leaves_the_file", "crates/redact/src/tests.rs::redaction_clears_pixels_intersected_without_covering_their_centres", "crates/redact/src/tests.rs::a_fax_image_has_its_covered_pixels_cleared_instead_of_being_removed", "crates/redact/src/tests.rs::group_3_on_bytes_is_removed_whole_and_other_fax_images_cleared", "crates/redact/src/tests.rs::an_image_whose_predictor_is_given_by_reference_has_the_covered_pixel_cleared", "crates/redact/src/tests.rs::a_jbig2_image_has_its_covered_pixels_cleared_instead_of_being_removed", "crates/redact/src/tests.rs::a_jbig2_image_that_cannot_be_cleared_for_certain_is_removed_whole", "crates/redact/src/tests.rs::a_redacted_jbig2_scan_keeps_neither_its_code_nor_its_globals", "crates/redact/src/tests.rs::a_cleared_black_and_white_scan_is_stored_as_group_4", "crates/redact/src/tests.rs::globals_a_redacted_jbig2_image_shares_with_another_page_leave_the_file"]
+notes = "intersected pixel footprints are cleared conservatively in a copy, CCITT fax and JBIG2 images (scans stored as Group 4 or JBIG2, with their /JBIG2Globals) included; DCT/JPX images, Group 3 on bytes (which the bootstrap renderer may draw as other rows than the decoder reads), and a JBIG2 image whose page isn't its size, removed whole. The copy is Flate, or for a one-bit image of one component Group 4, or JBIG2 when it was JBIG2, whichever is smallest as stored, and refers to no globals; whatever left the file takes its globals with it: what else names them, or an exact copy, is stored again without them (Flate, Group 4 or JBIG2, whichever is smallest), and apply refuses when one can't be. Not found: a dictionary holding the same shapes in other bytes. An image that hasn't left the file keeps its globals with its pixels: one another page draws, or one a pattern, soft mask or structure element refers to"
 
 [[feature]]
 id = "protect.redact-vectors"