1 files changed, 49 insertions, 5 deletions

diff --git a/working/context-engineering-rightsizing/metrics.org b/working/context-engineering-rightsizing/metrics.org
index 9cced4b..e7ff189 100644
--- a/working/context-engineering-rightsizing/metrics.org
+++ b/working/context-engineering-rightsizing/metrics.org
@@ -41,13 +41,36 @@ an afternoon instead of a week.
 
 *** T2 — Progressive disclosure preserves behavior (context-engineering post)
 
-*Claim.* Moving guidance out of always-loaded context into on-demand skills
+*Claim.* Moving guidance out of always-loaded context into on-demand loading
 doesn't degrade adherence.
 
-*Test.* The Phase 1 pilot. Detailed in Part 2.
+*ANSWERED 2026-07-27 for the deterministic half.* =/context= in a live work
+session lists 17 generic rules under Memory files, with the three path-scoped
+ones absent. Path-scoping is a glob match rather than a model judgment, so it
+either fires or doesn't, and it fires. That half needs no trial and no miss-rate
+metric.
 
-*Metric.* Miss rate per exposure. Mechanical, since four of the six pilot rules
-have a checker.
+*Still open for the semantic half.* Rules whose condition can't be a glob
+("when a commit is in play") route to skills, where triggering *is* a model
+judgment. Everything in Part 2 applies there and only there.
+
+*A caution the answer doesn't cover.* Path-scoping fires when Claude *reads* a
+matching file. A session that writes an org file without reading one first
+never triggers =todo-format.md=. Edit requires a prior read, so edits to
+existing files are safe; creating a new org file from scratch is the gap. Worth
+watching rather than blocking on.
+
+*** T3a — The token baseline was wrong by 45% [SETTLED]
+
+Word counts converted at a guessed ~1.3 tokens per word. The live number is
+2.28. =commits.md= is 12,800 tokens, not the ~7,000 estimated, and
+=claude-rules/= was ~57,800 tokens per session before today rather than the
+~33,000 implied.
+
+The lesson is narrower than "measure better." I had a real measurement
+available the whole time — =/context= reports per-file token counts — and used
+an estimate instead because the estimate was easier to compute from inside the
+repo. Reach for the instrument that reports the actual quantity.
 
 *** T3 — Deliverables run long without explicit calibration (Opus 5 guide)
 
@@ -63,7 +86,13 @@ call on whether anything useful was lost, which is the part I can't measure.
 *Baseline worth taking now,* since it costs one command and the before-number
 disappears the moment we change anything.
 
-*** T4 — Lower effort holds quality on mechanical passes (Opus 5 guide)
+*** T4 — Lower effort holds quality [WITHDRAWN 2026-07-27]
+
+Dropped with P4. The goal is output quality first, and this claim trades
+quality for cost, so testing it would answer a question we've decided not to
+act on either way.
+
+*** T4 (original text, retained for the record)
 
 *Claim.* =low= and =medium= produce strong quality at a fraction of the tokens.
 
@@ -212,6 +241,21 @@ Cheap now, impossible to reconstruct later:
 Item 1 is done. The rest are one session's work and should happen before
 Phase 0 changes the review skill, since that change contaminates item 4.
 
+* Instrument reliability — the day's second lesson
+
+The plan weights mechanical detectors over self-report because they have no
+stake. Two failed on 2026-07-27, both reporting success while doing damage:
+=wrap-org-table.el= reflowed a table into a worse shape and =lint-org= then
+certified it clean, and the wrap-teardown hook consumed a two-hour-old sentinel
+and killed a live work session that had done nothing wrong.
+
+Neither invalidates the preference for mechanical detectors, which is still
+right. Both narrow the claim: a detector has no stake, but it can be
+confidently wrong, and a green check from a guard that never looked at the
+thing is indistinguishable from a green check that did. When a detector clears
+a moved rule, the useful question is whether it actually evaluated it, not just
+whether it reported clean.
+
 * What this can and cannot tell us
 
 It can tell us whether on-demand loading fires reliably here, whether