Hypothesis test — cost-flattening of pattern-as-redirect Predicted 1 hour. Landed in 8 minutes 8 seconds. The git-url-refactor postmortem closed with a falsifiable claim. The second URL refactor measured it. 7.4× faster than predicted. DIMENSION PR #42 (FIRST) PR #53 (HYPOTHESIS TEST) VERDICT wall-clock (commit → live) an evening 8 min 8 sec ✓ confirmed files changed 19 17 comparable URL references rewritten 49 ~22 smaller scope Layer-1 helper LOC 13 13 ✓ identical sibling-test cases 9 12 covered Layer-3 wrapper 11 lines (Response + 301) 11 lines (copy-paste) ✓ identical sed-pass over-rewrites 0 1 (caught + fixed in 30s) ~ pattern risk verifier verdict before 7/7 ✓ 7/7 ✓ stable verifier verdict after 7/7 ✓ 7/7 ✓ stable test count delta +9 (379 → 388) +12 (407 → 419) net positive Cost-flattening hypothesis: CONFIRMED — much more dramatically than predicted. Predicted: 1 hour. Actual: 8m 8s. Ratio: 7.4× faster. The reusable shape (b32_<old>_url_redirect + sibling test + Layer-3 wrapper) collapses the URL-refactor wall-clock from "evening's work" to "coffee break". Same number of structural pieces; the cost of CONNECTING them was the bulk of the original effort, and that's now zero. One small pattern-risk surfaced: sed pattern matched inside filesystem paths (content/sama/sorted.md), caught by a unit test. https://tdd.md