re: reconcile the 49.6/92.3 split -- same numerator, and my explanation of it was wrong

sylpheed-port reconciled the population gap exactly and I reproduced it: filtering
max_t > 0 gives 1781 records and 92.3 %, their figures precisely. Same numerator,
1643, both ways.

My stated explanation was wrong. I said the scan requires a timed keyframe; it does
not, because .max() returns Some(0) rather than None for records whose keyframes are
all at time 0, so 1530 records where the question has no content stayed in my
denominator and counted as failures by construction.

The conclusion is untouched -- +0x04 is 0 % under either denominator.

Records their diagnosis of why it stayed invisible: the numerator agreed to the
unit, so a shared 1643 read as agreement and neither of us looked there. And both
halves needed a qualifier neither carried -- 92.3 % is of the records where the
question is meaningful, not of nested records.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

crates/sylpheed-formats/examples/loop_length_offset_discriminates.rs

@@ -45,6 +45,10 @@ fn main() {
                     .flat_map(|el| el.keyframes.iter().filter_map(|k| k.time))
                     .max();
                 let Some(max_t) = max_t else { continue };
+                // sylpheed-port's reconciliation: max_t == 0 makes "does the word
+                // equal the largest keyframe time?" vacuous, and those records were
+                // silently in my denominator. Filter them and the counts must meet.
+                if std::env::var("MEANINGFUL_ONLY").is_ok() && max_t == 0 { continue }
                 for (i, o) in offsets.iter().enumerate() {
                     if let Some(w) = be32(rec, *o) {
                         stat[i].0 += 1;

docs/re/METHOD.md

@@ -3235,3 +3235,26 @@ does not transfer to a per-record header: **an interior consistency check is
 satisfied by any reading that is internally consistent — and "internally
 consistent" is what a wrong offset into a regular structure usually is.** The
 boundary rule is the special case where the structure's edges break that regularity.
+
+## A denominator mismatch hides behind an agreeing numerator
+
+Two agents, one statistic, and the disagreement was **entirely in the denominator**:
+`1643/1781 = 92.3 %` against `1643/3311 = 49.6 %`. **Neither of us was wrong about
+the disc.**
+
+🔴 **My explanation of the gap was wrong too.** I said my scan "requires a timed
+keyframe". It does not — `.max()` over the keyframe times returns `Some(0)`, not
+`None`, for a record whose keyframes all sit at time 0, so those never left my
+denominator. 1 530 records where *"does the word equal the largest keyframe time?"*
+has **no content** were counted as failures **by construction**.
+
+📌 **`sylpheed-port`'s diagnosis of why it stayed invisible is the transferable
+part: the numerator agreed to the unit.** We both looked at **1 643** and neither
+noticed we were dividing it differently. An agreeing numerator reads as agreement,
+and a shared number is the last place either party looks for a discrepancy.
+
+⚠️ **Both halves needed a qualifier neither carried.** 92.3 % is *of the records
+where the question is meaningful*, not *of nested records* — quoted bare on both
+sides for two days, including into a shipped doc comment. **A population-scoped
+statistic reported without its population is the same shape as a negative reported
+without its reach**, and this corpus already had a rule for the second.

docs/re/structures/ui-record-loop-length.md

@@ -22,10 +22,27 @@ disc-wide (1 781 records, 0 violations).
 > a secondary statistic**: `+0x08` equals the largest keyframe time *exactly* in
 > half the records and `+0x04` in **none**. No unrelated word reproduces that.
 >
-> ⚠️ My population differs from theirs — 3 311 records against 1 781, because this
-> scan takes every pak and requires a timed keyframe — so the exact percentage
-> moves (49.6 % vs 92.3 %). **The discrimination does not**: 0 % for `+0x04` under
-> both counts. The consequence for the `PRESS Ⓐ` plate
+> 🔴 **AND MY EXPLANATION OF THE 49.6 % WAS WRONG.** I wrote that my scan "requires
+> a timed keyframe", so the population differed. It does not: `.max()` over the
+> keyframe times returns `Some(0)` — not `None` — for a record whose keyframes are
+> all at time 0, so those never left my denominator. `sylpheed-port` reconciled it
+> exactly and I reproduced it:
+>
+> ```
+> 1643 / 1781 = 92.3 %   records where max t > 0 — the question is meaningful
+> 1643 / 3311 = 49.6 %   plus 1 530 records where max t == 0
+> ```
+>
+> **Same numerator.** The 1 530 extra are records where *"does the word equal the
+> largest keyframe time?"* has no content — `max t` is 0, so each counts as
+> not-exact **by construction**. 49.6 % is not a weaker 92.3 %; it is 1 643
+> successes over a denominator containing 1 530 questions that were never asked.
+>
+> ✅ **The conclusion is untouched**: `+0x04` is **0 %** under either denominator,
+> so the offset stands on both scans.
+>
+> ⚠️ **And 92.3 % needs the qualifier it has never carried here**: it is *of the
+> records where the question is meaningful*, not *of nested records*. The consequence for the `PRESS Ⓐ` plate
 is then tested against the corpus's existing measurements of the running game,
 which it passes and the previous reading fails.