repo-mailbox/docs/2026-09-03-coordination-debt-measurement.md

Coordination debt: what does not converge, and why building a second

mechanism would have been wrong

Measured 2026-09-03 against the live mailbox, for order 20260902T113745Z-1254925290-from-.claude (WP5). Every number below was produced by a command, and every negative result carries the control that proves the query could have found something.

The order offered two candidate mechanisms and said to choose by measurement, not taste: a broadcast TTL, or a bulk-ack for pure notices. The measurement chose neither. One of them is already built and has never been run; the other addresses the class that converges on its own.

Denominators

population	count
mailbox directories under the coord root	55
of those, holding an inbox/	52
pending directed messages across all inboxes	27
broadcasts in _broadcast/inbox/	17
(mailbox x broadcast) delivery pairs	884

The three directories with no inbox/ are named rather than silently dropped: jobbsok, mediemon, medieovervaaking. 55 - 3 = 52 is the reconciliation, stated because an unreconciled pair of denominators in one report is the same positive-looking null this engine refuses everywhere else.

The two classes behave in opposite directions

Directed messages do not converge. They are re-injected at every session start until a session closes them by hand. Of the 27 pending, 4 owe a reply and 23 are pure notices (reply-expected: no). By age:

class	<7d	7-13d	14-29d	>=30d
owes a reply	0	3	1	0
pure notice	10	6	7	0

Broadcasts converge on their own. Reading one records it as seen, so a mailbox clears its whole backlog on its next session. 263 of the 884 pairs are unread (29.8%), and the distribution shows the self-clearing: 10 mailboxes are fully current, 26 sit at exactly 6 unread (the newest announcements), and the tail is short.

The floor under the broadcast number, which strengthens the case

Two mailboxes hold all 17 broadcasts unread, and neither can ever read them:

• ktg-plugin-marketplace is a retired --to address. It is a polyrepo directory, not a git repo, so basename(git toplevel) can never resolve to it and no session can hold that identity. This is already documented as engine behaviour; the 17 unread are its permanent consequence.
• llm-ingestion-guard has no checkout anywhere under /Users/ktg (find -maxdepth 4, with llm-ingestion-okf as the known-positive control proving the query finds a real one) and no .origin. It also holds the single oldest pending notice, 24 days.

So 34 of 263 unread pairs (12.9%) are a permanent floor no TTL would reduce to zero - it would close them, but it would be closing announcements for mailboxes that were never going to read anything. .origin absence alone is NOT a proxy for unholdable: repos also lacks one, yet sits at 2 unread of 17, which is only possible if something reads it.

Why no second mechanism was built

coord-sweep.sh already is the bulk-ack for pure notices: machine-wide, one mechanically decidable class (reply-expected: no, older than a grace window), dry-run by default, closing through coord-done.sh, logging sender and subject for every closure. Building the order's second candidate would have been a second copy of a shipped policy - the defect class this repo names repeatedly.

Its own dry-run reports what it would close today, and the figures agree exactly with the independent classification above:

--days 30  ->  0 messages
--days 14  ->  7 messages
--days  7  -> 13 messages

The gap is invocation, not mechanism. No _sweep.log exists at the default path, and no sweep log exists anywhere under ~/.claude (the one *sweep* hit is an unrelated plugin file) - stated that way because --log can override the default, so an absent default-path log alone would not prove it never ran.

What remains, and why it is not this repo's call

Making the notice class converge without opening each repo means running coord-sweep.sh --write unattended. That closes mail in 51 other repos' inboxes, unread, and the script's own design says so in as many words: a notice to a repo left unopened for the whole window is closed unread, and the log is the only thing standing between that and a silent disappearance.

Deciding that on another repo's behalf is the one anti-pattern with no exception clause, and the grace window is a policy constant of the same class as the STATE.md line limit, which was an operator decision both times it moved. Dry-run is the default precisely because this is the script that destroys pending state; flipping that to a schedule is the operator's act, not a plugin's.

The messages that owe a reply are untouched by any of this, at any age, with any flag. That is not a gap to close later - it is the rule that keeps a procedural duty from becoming a substantive one.