The largest unforced error in the plan. Every quantitative conclusion in the roadmap is a function of p, the per-atom merge-time failure rate, and it has never been measured. There is currently no instrument in the design that could measure it without first taking exclusive write access to someone's trunk.
p decides: the drainability wall (p* = 1/(1+lambda*E[S]) — 24.2% sustained, 11.3% peak at our envelope), required speculation width, the entire cost table, Bar B's thresholds, cohort size n*, and whether the attribution design is even the maximum-likelihood answer.
Decompose it into four components, because only one of them justifies a merge queue at all. Every atom already passed its own PR CI before enqueue, so a merge-time failure is exactly one of:
- (a) stale base — solved by requiring up-to-date branches, no queue needed
- (b) spurious red
q — a test-quality problem invariant 6 puts irreducibly into the throughput budget
- (c) genuine interaction
r — the thing a merge queue uniquely prevents. This is the number that decides whether the product has a reason to exist.
- (d) replay conflict
c — a separate absorbing state costing zero CI, strongly correlated rather than independent, compounding with prefix depth as 1-(1-c)^k. Plausibly binds speculation depth before p does at monorepo scale.
Eight independent analyses agreed p was the pivot and every one modelled it as a single number.
The strongest argument FOR the premise, which nobody in the corpus made: interaction failures scale as C(n,2)*r in the number of changes merging per CI window, so the case for a queue grows quadratically with agent concurrency while the case for merely faster CI grows only linearly.
Build: read-only shadow mode. contents:read, pull_requests:read, checks:read. For every merged PR, reconstruct the candidate the queue would have built using the existing merge-tree path. Yields c at zero CI spend, plus stack prevalence and depth distribution. On any repo already running GitHub MQ, harvest merge_group check conclusions as a free verdict oracle for p.
Cost: roughly what the M0a kernel cost. ~$0 CI. No trunk write access — that is the point. Unblocks W3's baseline, M2's width decision, and de-risks Bar A.
See docs/INVESTIGATION.md §6 Q1, §7 R3, §8 E1.
The largest unforced error in the plan. Every quantitative conclusion in the roadmap is a function of
p, the per-atom merge-time failure rate, and it has never been measured. There is currently no instrument in the design that could measure it without first taking exclusive write access to someone's trunk.pdecides: the drainability wall (p* = 1/(1+lambda*E[S])— 24.2% sustained, 11.3% peak at our envelope), required speculation width, the entire cost table, Bar B's thresholds, cohort sizen*, and whether the attribution design is even the maximum-likelihood answer.Decompose it into four components, because only one of them justifies a merge queue at all. Every atom already passed its own PR CI before enqueue, so a merge-time failure is exactly one of:
q— a test-quality problem invariant 6 puts irreducibly into the throughput budgetr— the thing a merge queue uniquely prevents. This is the number that decides whether the product has a reason to exist.c— a separate absorbing state costing zero CI, strongly correlated rather than independent, compounding with prefix depth as1-(1-c)^k. Plausibly binds speculation depth beforepdoes at monorepo scale.Eight independent analyses agreed
pwas the pivot and every one modelled it as a single number.The strongest argument FOR the premise, which nobody in the corpus made: interaction failures scale as
C(n,2)*rin the number of changes merging per CI window, so the case for a queue grows quadratically with agent concurrency while the case for merely faster CI grows only linearly.Build: read-only shadow mode.
contents:read,pull_requests:read,checks:read. For every merged PR, reconstruct the candidate the queue would have built using the existing merge-tree path. Yieldscat zero CI spend, plus stack prevalence and depth distribution. On any repo already running GitHub MQ, harvestmerge_groupcheck conclusions as a free verdict oracle forp.Cost: roughly what the M0a kernel cost. ~$0 CI. No trunk write access — that is the point. Unblocks W3's baseline, M2's width decision, and de-risks Bar A.
See
docs/INVESTIGATION.md§6 Q1, §7 R3, §8 E1.