diff --git a/data-raw/measure_signposting_rate.R b/data-raw/measure_signposting_rate.R
index 51bc456..00492f7 100644
--- a/data-raw/measure_signposting_rate.R
+++ b/data-raw/measure_signposting_rate.R
@@ -1,8 +1,8 @@
 # data-raw/measure_signposting_rate.R
 #
 # Phase R3 Task 19c: measures the harmonization-signposting suggestion rate
-# under BOTH the R2 "coarse" (whole-result) gap check and the R3 "per-code"
-# gap check now shipped in R/suggestions.R, over a realistic query battery:
+# under THREE `.build_suggestions()` implementations, over a realistic query
+# battery:
 #   every summary_categories category
 #     x a 3-year pre/post-2012 span (the wide-aggregate -> modern-leaf
 #       format-boundary window; falls back to the widest span the corpus
@@ -10,19 +10,37 @@
 #       .measure_year_span())
 #     x up to N_GOV sampled governments (seeded, deterministic)
 #
-# This script MEASURES the coarse-vs-per-code delta; it does not decide
-# whether that much added signposting "noise" is acceptable. That is
-# Jared's ruling at Checkpoint R3 (see
-# cog_pipeline/.superpowers/sdd/phase-r-task-19c-brief.md).
+# The three arms, oldest to newest:
+#   - "coarse"  (git ref b0df1ec, the merged R2 tip): a year counts as
+#     gapped only when the WHOLE category result has zero rows that year.
+#   - "selfcov" (git ref da72bf3, Task 19c's first per-code pass, since
+#     amended after review): per-code, but a component's gap could be
+#     satisfied by ANY component of the recipe INCLUDING ITSELF -- so a
+#     code whose only representation in a year was its own wide-era
+#     aggregate row satisfied its own coverage check. Flagged in review as
+#     not matching review-doc S: 0.3's literal criterion ("... has no rows
+#     ... but OTHER components do") and fixed in the next commit.
+#   - "percode" (live code): per-code, requiring a genuinely DIFFERENT
+#     sibling component to supply the covering evidence -- the shipped,
+#     corrected implementation.
 #
-# The R2 "coarse" implementation no longer exists in R/suggestions.R (Task
-# 19c replaced it in place with the per-code version), so this script pulls
-# it VERBATIM from git history (default ref: b0df1ec, the merged tip of the
-# R2 branch) and evaluates it in an isolated environment parented on the
-# uscogdata namespace, so it still resolves unchanged helpers it depends on
-# (.sql_lit_chr()) exactly as the live package does. This guarantees the
-# "coarse" arm is the actual shipped R2 code, not a hand-reconstruction of
-# it that could silently drift from what really shipped.
+# This script MEASURES the deltas; it does not decide whether the added
+# signposting "noise" going coarse -> percode is acceptable. That is
+# Jared's ruling at Checkpoint R3 (see
+# cog_pipeline/.superpowers/sdd/phase-r-task-19c-brief.md). The selfcov arm
+# exists purely to answer a narrower, mechanical question for that ruling:
+# how much of the coarse -> percode delta was ever attributable to the
+# self-coverage bug (selfcov -> percode), as opposed to genuine
+# other-component coverage (coarse -> percode directly)?
+#
+# All three arms no longer coexist in R/suggestions.R (each superseded the
+# last in place), so this script pulls each VERBATIM from git history and
+# evaluates it in an isolated environment parented on the uscogdata
+# namespace, so each still resolves the unchanged sibling helpers it
+# depends on (.sql_lit_chr()) exactly as the live package did at that
+# commit. This guarantees every non-live arm is the actual shipped code at
+# that point, not a hand-reconstruction that could silently drift from what
+# really shipped.
 #
 # Usage (from the uscogdata package root; a git checkout, not a tarball):
 #   Rscript data-raw/measure_signposting_rate.R
@@ -33,13 +51,12 @@
 #   res <- measure_signposting_rate(corpus_url = "<url>")
 #   res$summary; res$by_category
 
-#' Pull the R2-era (coarse, whole-result) `.build_suggestions()` verbatim
-#' from git history and evaluate it in an isolated environment parented on
-#' the uscogdata namespace, so it resolves unchanged sibling helpers
-#' (`.sql_lit_chr()`) the same way the live package does.
+#' Pull a historical `.build_suggestions()` (and whatever helpers it uses)
+#' verbatim from git history and evaluate it in an isolated environment
+#' parented on the uscogdata namespace, so it resolves unchanged sibling
+#' helpers (`.sql_lit_chr()`) the same way the live package does.
 #' @noRd
-.measure_load_coarse_impl <- function(git_ref = "b0df1ec",
-                                       git_path = "R/suggestions.R") {
+.measure_load_git_impl <- function(git_ref, git_path = "R/suggestions.R") {
   old_src <- tryCatch(
     system2("git", c("show", sprintf("%s:%s", git_ref, git_path)),
             stdout = TRUE, stderr = TRUE),
@@ -49,7 +66,7 @@
   if (is.null(old_src) || (!is.null(status) && status != 0L) ||
       !any(grepl("^\\.build_suggestions", old_src))) {
     stop(
-      "Could not retrieve the R2 .build_suggestions() implementation from ",
+      "Could not retrieve the .build_suggestions() implementation from ",
       "git ref '", git_ref, "' at '", git_path, "'. Run this script from ",
       "inside the uscogdata git checkout (not a tarball/installed copy).",
       call. = FALSE
@@ -58,10 +75,9 @@
   env <- new.env(parent = asNamespace("uscogdata"))
   # eval(parse()) here is safe: `old_src` is not external/untrusted input --
   # it is this repo's OWN historical R/suggestions.R, fetched via `git show`
-  # from a fixed, hardcoded internal commit ref (default b0df1ec, the merged
-  # R2 tip; overridable only by a caller who already has R-level code
-  # execution in this dev-only measurement script). No network or
-  # user-supplied data reaches this call.
+  # from a fixed, hardcoded internal commit ref (overridable only by a
+  # caller who already has R-level code execution in this dev-only
+  # measurement script). No network or user-supplied data reaches this call.
   eval(parse(text = old_src), envir = env)
   stopifnot(is.function(env$.build_suggestions))
   env
@@ -129,12 +145,12 @@
   sort(sample(pool, n))
 }
 
-#' Run one (category, government) query through both the coarse (git ref
-#' `coarse_env`) and current per-code `.build_suggestions()` and return a
-#' one-row summary of what each one fired.
+#' Run one (category, government) query through the coarse (`coarse_env`),
+#' self-coverage-allowed (`selfcov_env`), and live per-code
+#' `.build_suggestions()` and return a one-row summary of what each fired.
 #' @noRd
-.measure_one_query <- function(con, coarse_env, category, category_type,
-                                govid, years) {
+.measure_one_query <- function(con, coarse_env, selfcov_env, category,
+                                category_type, govid, years) {
   view        <- if (identical(category_type, "revenue")) {
     "revenue_annotated_harmonized"
   } else {
@@ -151,6 +167,9 @@
   coarse_sugg  <- coarse_env$.build_suggestions(
     con, govid, years, category, result, "harmonized"
   )
+  selfcov_sugg <- selfcov_env$.build_suggestions(
+    con, govid, years, category, "harmonized"
+  )
   percode_sugg <- .build_suggestions(con, govid, years, category, "harmonized")
 
   data.frame(
@@ -159,8 +178,10 @@
     canonical_govid = govid,
     n_result_rows   = nrow(result),
     n_coarse        = length(coarse_sugg),
+    n_selfcov       = length(selfcov_sugg),
     n_percode       = length(percode_sugg),
     fired_coarse    = length(coarse_sugg) > 0L,
+    fired_selfcov   = length(selfcov_sugg) > 0L,
     fired_percode   = length(percode_sugg) > 0L,
     stringsAsFactors = FALSE
   )
@@ -183,7 +204,10 @@
 #'   with `post_years_n` years starting at `boundary_year`. Falls back to
 #'   the corpus's widest actually-available span when this can't be filled
 #'   (see `.measure_year_span()`).
-#' @param git_ref Git ref to pull the R2 coarse `.build_suggestions()` from.
+#' @param coarse_ref Git ref to pull the R2 coarse `.build_suggestions()`
+#'   from.
+#' @param selfcov_ref Git ref to pull Task 19c's first, self-coverage-
+#'   allowed per-code `.build_suggestions()` from (amended after review).
 #' @param verbose Print progress/notes as the battery runs.
 #' @return Invisibly, a list with `corpus_url`, `years`, `span_note`,
 #'   `full_design`, `govids`, `seed`, `detail` (one row per query),
@@ -195,7 +219,8 @@ measure_signposting_rate <- function(corpus_url = Sys.getenv("USCOGDATA_URL", un
                                       boundary_year = 2012L,
                                       pre_years_n = 3L,
                                       post_years_n = 3L,
-                                      git_ref = "b0df1ec",
+                                      coarse_ref = "b0df1ec",
+                                      selfcov_ref = "da72bf3",
                                       verbose = TRUE) {
   pkgload::load_all(".", quiet = TRUE)
 
@@ -218,7 +243,8 @@ measure_signposting_rate <- function(corpus_url = Sys.getenv("USCOGDATA_URL", un
   }, add = TRUE)
 
   con <- cog_open()
-  coarse_env <- .measure_load_coarse_impl(git_ref = git_ref)
+  coarse_env  <- .measure_load_git_impl(git_ref = coarse_ref)
+  selfcov_env <- .measure_load_git_impl(git_ref = selfcov_ref)
 
   span   <- .measure_year_span(con, boundary_year, pre_years_n, post_years_n)
   years  <- span$years
@@ -249,7 +275,7 @@ measure_signposting_rate <- function(corpus_url = Sys.getenv("USCOGDATA_URL", un
     for (gv in govids) {
       k <- k + 1L
       rows[[k]] <- .measure_one_query(
-        con, coarse_env,
+        con, coarse_env, selfcov_env,
         category = categories$category[ci],
         category_type = categories$category_type[ci],
         govid = gv, years = years
@@ -257,28 +283,41 @@ measure_signposting_rate <- function(corpus_url = Sys.getenv("USCOGDATA_URL", un
     }
   }
   detail <- do.call(rbind, rows)
+  # percode only ever fires where selfcov also fires (percode is a strict
+  # narrowing of selfcov: same gap detection, plus the self-coverage path
+  # removed) -- this is what makes the decomposition below exact rather
+  # than approximate. Checked, not assumed.
+  stopifnot(all(detail$fired_percode <= detail$fired_selfcov))
+  detail$fired_selfcov_only <- detail$fired_selfcov & !detail$fired_percode
 
   by_category <- dplyr::summarise(
     dplyr::group_by(detail, category, category_type),
     n_queries      = dplyr::n(),
     coarse_rate    = mean(fired_coarse),
+    selfcov_rate   = mean(fired_selfcov),
     percode_rate   = mean(fired_percode),
-    delta_pp       = (mean(fired_percode) - mean(fired_coarse)) * 100,
+    original_delta_pp  = (mean(fired_selfcov) - mean(fired_coarse)) * 100,
+    corrected_delta_pp = (mean(fired_percode) - mean(fired_coarse)) * 100,
+    selfcov_share_pp    = mean(fired_selfcov_only) * 100,
     .groups = "drop"
   )
-  by_category <- dplyr::arrange(by_category, dplyr::desc(delta_pp))
+  by_category <- dplyr::arrange(by_category, dplyr::desc(corrected_delta_pp))
 
   summary_overall <- data.frame(
     n_queries     = nrow(detail),
     n_categories  = nrow(categories),
     n_governments = length(govids),
     coarse_fired  = sum(detail$fired_coarse),
+    selfcov_fired = sum(detail$fired_selfcov),
     percode_fired = sum(detail$fired_percode),
     coarse_rate   = mean(detail$fired_coarse),
+    selfcov_rate  = mean(detail$fired_selfcov),
     percode_rate  = mean(detail$fired_percode)
   )
-  summary_overall$delta_pp <- (summary_overall$percode_rate - summary_overall$coarse_rate) * 100
-  summary_overall$relative_increase <- if (summary_overall$coarse_rate > 0) {
+  summary_overall$original_delta_pp  <- (summary_overall$selfcov_rate - summary_overall$coarse_rate) * 100
+  summary_overall$corrected_delta_pp <- (summary_overall$percode_rate - summary_overall$coarse_rate) * 100
+  summary_overall$selfcov_share_pp   <- mean(detail$fired_selfcov_only) * 100
+  summary_overall$relative_increase  <- if (summary_overall$coarse_rate > 0) {
     summary_overall$percode_rate / summary_overall$coarse_rate - 1
   } else {
     NA_real_
@@ -286,10 +325,16 @@ measure_signposting_rate <- function(corpus_url = Sys.getenv("USCOGDATA_URL", un
 
   if (verbose) {
     message(sprintf(
-      "Coarse rate: %.4f (%d/%d)  |  Per-code rate: %.4f (%d/%d)  |  Delta: %+.2f pp",
+      "Coarse rate: %.4f (%d/%d)  |  Self-cov-allowed rate: %.4f (%d/%d)  |  Corrected per-code rate: %.4f (%d/%d)",
       summary_overall$coarse_rate, summary_overall$coarse_fired, summary_overall$n_queries,
-      summary_overall$percode_rate, summary_overall$percode_fired, summary_overall$n_queries,
-      summary_overall$delta_pp
+      summary_overall$selfcov_rate, summary_overall$selfcov_fired, summary_overall$n_queries,
+      summary_overall$percode_rate, summary_overall$percode_fired, summary_overall$n_queries
+    ))
+    message(sprintf(
+      "Original delta (selfcov - coarse): %+.2f pp  |  Corrected delta (percode - coarse): %+.2f pp  |  Self-coverage share of original delta: %.2f pp (%d/%d queries fired ONLY via self-coverage)",
+      summary_overall$original_delta_pp, summary_overall$corrected_delta_pp,
+      summary_overall$selfcov_share_pp,
+      sum(detail$fired_selfcov_only), summary_overall$n_queries
     ))
   }
 
@@ -316,9 +361,9 @@ if (identical(environment(), globalenv()) && sys.nframe() == 0L) {
   cat(res$span_note, "\n")
   cat("Governments sampled:", length(res$govids), "\n\n")
 
-  cat("==== Overall summary ====\n")
+  cat("==== Overall summary (coarse / self-coverage-allowed / corrected per-code) ====\n")
   print(res$summary)
 
-  cat("\n==== By category (sorted by delta, descending) ====\n")
+  cat("\n==== By category (sorted by corrected delta, descending) ====\n")
   print(as.data.frame(res$by_category), row.names = FALSE)
 }