Review found the first version generating every envelope with an empty causal
context. Production gives only the root that shape: each later edit carries
active_prior_context(), the head's context extended by the head, so it covers
the whole active prefix. Reduction orders on those edges, so a context-free log
exercises a different algorithm -- and a cheaper one. Counters were wrong the
same way: EditorSession mints at authored.len(), so the root is counter zero,
which is also what extend_context recognises as the start of a contiguous run.
Remeasured on a session-shaped log, reduce is roughly three times its former
self at depth ten thousand -- 54 ms, not 17 -- and the wall moves from about ten
thousand edits to between three and five thousand. That is the number T4b is
sequenced against, so the first table would have mis-sequenced it. Depths three
and five thousand now bracket the crossing; sampling only decades hid it.
Two findings survive the correction and one is weakened. Reduce is still the
only depth-scaling stage, and is superlinear at about n^1.4 -- which does not
contradict the reduction bench's subquadratic result at fifty thousand
envelopes, because that log is generated across three replicas with a different
causal shape, and two logs of equal length are not equal work. Engrave is still
flat, at 260 to 327 microseconds, and is still the larger half of the core's
portion at shallow depth, so criterion 2's "uninformative while reduction
dominates" holds only past roughly depth five hundred. But "render dominates at
realistic depths" is now bounded: paint leads by four and a half times at depth
one hundred, is level by one thousand, and is left behind after. T4 before T4b
still stands -- the canvas removes what dominates a session's first thousand-odd
edits -- but the two are no longer comfortably separated.
The gate now includes envelope construction, which the requirement names first
and the first version silently dropped. It is forty nanoseconds and never moves
a verdict; a gate that omits a named component is a proxy for the requirement
rather than the requirement.
The 98% claim is replaced by both figures with their denominators named: what a
direct-IR canvas avoids is 83% of the full measured per-edit pipeline, and 99.8%
of the render path alone. The unqualified number was supported by neither.
One row changed marking for a reason worth recording. Depth four thousand passes
clean at 12.99 ms, but that is 78% of budget, and a load-contaminated run
measured it at 22.77 ms -- above the five thousand row, which is impossible
clean. A Pass row that fails whenever the machine is busy teaches people to
ignore the gate, so the last gated Pass is three thousand and four thousand's
clean number is kept as data in the table instead.
Also recorded: depth is per session, not per document. EditorSession::open
starts with an empty applied log, so reopening resets it and the reduced score
becomes the new pristine base. That is what keeps a four-figure wall from being
catastrophic -- though note entry mints one operation per note, so it is
reachable in a sitting.
Verified in an isolated worktree at HEAD rather than in the working tree, which
currently carries the genesis tranche's in-flight G2 work: fmt clean, clippy 0
with and without golden-gate, workspace tests green, gate OK across all five
rows.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RSX4zSLgKvtiXaPjnMqLGz
Levi Neuwirth
986c9cc5a1