qr: every version, 1 to 40

PSOGM mode will put the kernel log on screen as QR codes, a page per
symbol, and version 6 held 134 bytes. Version 40 at level L holds 2,953.

What grew: blocks of two lengths and the interleave that steps around
them, the alignment-pattern grid, the version-information blocks from
version 7, the 16-bit character count from version 10. The per-version
table is down to the two columns that are genuinely transcription (EC
codewords per block, block count); total codewords come from the
geometry.

Checked against segno module for module at every version (exact-fill
payloads), and 120 symbols across all 40 versions decode with zbar.
OpenCV's detector cannot find symbols above about version 24 at all,
segno's included, so qrcheck reports those as the detector's limit.

The crash card stays a version-6 symbol (QR_CARD_BYTES), so a phone still
reads it from across the desk.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

tools/python/qrcheck.py

@@ -117,10 +117,15 @@ def decode(m):
     return ""
 
 
-# Byte capacity per version: total - ecc*blocks - 2. Mirrors the table in qr.c;
-# the exact-fill cases below are built from it, and a disagreement would show up
+# Byte-mode capacity per version at level L, from ISO/IEC 18004 table 7 --
+# written out rather than computed, so it checks qr.c instead of agreeing with
+# it. The exact-fill cases below are built from it, and a disagreement shows up
 # as a version mismatch rather than passing quietly.
-CAPACITY = {1: 17, 2: 32, 3: 53, 4: 78, 5: 106, 6: 134}
+CAPACITY = dict(enumerate([
+    17, 32, 53, 78, 106, 134, 154, 192, 230, 271, 321, 367, 425, 458, 520,
+    586, 644, 718, 792, 858, 929, 1003, 1091, 1171, 1273, 1367, 1465, 1528,
+    1628, 1732, 1840, 1952, 2068, 2188, 2303, 2431, 2563, 2699, 2809, 2953,
+], start=1))
 
 alpha = lambda n: "".join(chr(65 + i % 26) for i in range(n))
 
@@ -133,8 +138,9 @@ CASES = [
     bytes(range(1, 40)).decode("latin-1"),          # non-printable payload
 ]
 # One payload that exactly fills each version, and one just under, so both the
-# padded and unpadded paths are covered at every version -- including 6, which
-# is the only one with more than one Reed-Solomon block.
+# padded and unpadded paths are covered at every version: several Reed-Solomon
+# blocks from 6, blocks of two lengths from 6 too, the version information
+# from 7, the 16-bit character count from 10.
 for v, cap in CAPACITY.items():
     CASES.append(alpha(cap))
     CASES.append(alpha(cap - 1))