docs: user guide, known limitations and M8 results; bump to 0.8.0v0.8.0

0.8.0 is the release candidate: 1.0.0 is tagged after the on-watch
checklist (docs/TESTING.md).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7ac63f2..892d7a2 100644
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+++ b/CHANGELOG.md
@@ -11,6 +11,62 @@ All notable changes to this project are documented here. The format follows
 
 ## [Unreleased]
 
+## [0.8.0] - 2026-10-21
+
+Milestone M8: polish, performance and the release candidate. 1.0.0 follows
+once the on-watch checklist is done (docs/TESTING.md).
+
+### Added
+
+- The favourite code in the glance (opt-in, "Show the favourite code in the
+  glance"): the first favourite TOTP or Steam entry without the PIN, with a
+  countdown bar. The app seals that entry for the glance under `g` after
+  every change (`source/app/GlanceCode.mc`); the glance checks the option
+  itself, so turning it off hides the code at once.
+- Manage entry: "Mark as favourite (glance)" and "Remove favourite".
+- Brightness: full brightness on AMOLED watches and the backlight on MIP
+  watches while a barcode is shown, renewed for up to a minute; a tap starts
+  the minute again.
+- `make watchdog` (in `make ci`): a stress build (`stress.jungle`,
+  `source/util/StressTest.mc`) encodes the largest code of every 2D
+  symbology, packs it, finds its runs and draws it, with two steps per
+  event, on the Forerunner 255S and 70. The last code stays on the screen
+  and must decode.
+- `make memtest` checks the glance too (at most 70 % of its 64 KB).
+- `make products` checks each product's watchdog limit against the job
+  runner's assumption.
+- `docs/USER_GUIDE.md`, with the list of known limitations.
+
+### Changed
+
+- Imports use far less memory: parsed items are kept packed (about 110
+  bytes each instead of 760 as objects), and the pasted text is held once.
+  The peak of a 100-entry import on the Forerunner 255S fell from 56 % to
+  45 % of its memory.
+- QR mask scoring works on rows and columns packed 16 modules per word
+  (the same penalties as before, checked against the per-module rules on
+  every mask): a version 10 QR takes 40 % less compute.
+- Watches with 768 KB (every target except the Forerunner 255 and 255S) run
+  two job steps per timer tick, which halves import and encoding times.
+- Large 2D codes are drawn as runs (one rectangle per run), from a bitmap
+  painted in steps when there are too many runs for one frame.
+- The barcode cache has a new format with 16-bit sizes; caches from 0.7 are
+  re-encoded once.
+
+### Fixed
+
+- Large 2D codes could stop the app with "Watchdog Tripped" on every watch:
+  the QR segmentation, Reed-Solomon blocks, function patterns and the final
+  mask; Data Matrix encodation, placement and drawing; Aztec bit encoding,
+  stuffing, the GF(4096) tables and generator; PDF417 compaction; the cache
+  packing; and drawing a code module by module. Every step is now bounded
+  and measured (`make watchdog`). An entry like that added from the phone
+  would have crashed the app during settings processing, at every start.
+- A PDF417 code wider than 255 modules (big screens) was cached with a
+  wrong width.
+- The Data Matrix placement grid used up to 90 KB; it now uses a byte
+  array (about 35 KB for the largest symbol).
+
 ## [0.7.0] - 2026-10-20
 
 Milestone M7: the phone settings forms. Entries can now be added and changed