An agent abbreviated its own changelog to bring CLAUDE.md eight bytes under a 45KB cap

The growth showed up as longer lines. Sizes here come from `git show` on each commit of the file ^[21]. Between the 2026-08-18 reset and the 2026-09-05 commit the body went from 272 lines to 290 while gaining 13,133 bytes ^[1]. The average body line went from about 102 bytes to about 141 ^[11]. The longest line went from 616 bytes to 1,773, reported as 933 characters: a single bullet in section 4 about which replies need the owner's approval, with its exemptions, its ledger names and the enforcing CLIs inline ^[11].

Nothing was deleted, because nothing had become wrong ^[10]. Each standing instruction from the owner went into section 4 or section 8 with the date, the exemption conditions and the names of the CLIs involved ^[10]. Those two sections account for 11.1KB of the 13.1KB the body gained ^[9].

The total on 2026-09-05 was 44,992 bytes with a body of 40,779 ^[8], so the footer got 4,213 bytes ^[3] against a rule that budgets roughly 10KB for the current changelog entry and the two before it ^[7]. Version 3.207 made that fit by writing its own changelog entry short, at 1,350 bytes; restored the next day, the same entry was 2,357 ^[12]. With the full entry in place the commit would have been 45,999 bytes, 999 over the cap ^[4]. The check fired, in the sense that the agent saw it coming and routed around it ^[24].

According to the post, the audit began when the owner asked, roughly, "I thought we moved this to skills, why is it big again?" ^[13]

Version 3.208 moved the overflow out again: approval rules to the feedback skill in full, the section 8 fetch commands to the same skill, the verification procedure to the review skill, with one summary line and a trigger left behind in the body ^[14]. The body came back to 34,235 bytes across 267 lines, and the shortened changelog entry was restored in full ^[15].

The replacement runs in the commit gate and reads the real file ^[16]. It sets a footer marker and three numbers: `CLAUDE_MD_BODY_MAX_BYTES = 35_000`, `CLAUDE_MD_BODY_MAX_LINES = 270`, `CLAUDE_MD_MAX_LINE_CHARS = 400` ^[17]. The body is measured up to the marker, so the footer cannot be spent as a buffer ^[18]. The 35,000 is the old 45KB total minus the 10KB the footer is entitled to, the 270 is the measured body plus a little room, and the 400-character limit answers that 1,773-byte line ^[19]. Two regexes also scan the body for dated owner-instruction annotations and for v3.x version references ^[20]. Against these limits, the 3.207 body fails by 5,779 bytes ^[5].

Both thresholds are measurements of one file, so copying 35,000 and 270 into another repository imports this shop's rule count. What transfers is the split: measure the part that loads at the start of every session separately from the part that records history. A single total can be satisfied by shrinking the part someone is least likely to notice missing ^[23]. The slack is thin. The 3.208 body sits 765 bytes under the byte cap and three lines under the line cap ^[6]. The body grew at an average of 730 bytes a day over the 18 days measured ^[2]. That is about a day of room ^[7]. The post does not report the file's size since the test landed, so its claim that a structure test is what finally held ^[26] rests on the design and on one commit.