diff --git a/tests/testthat/helper-fixture.R b/tests/testthat/helper-fixture.R
index 30c7225..47f0726 100644
--- a/tests/testthat/helper-fixture.R
+++ b/tests/testthat/helper-fixture.R
@@ -6,6 +6,33 @@ fixture_corpus_path <- function() {
   if (nzchar(p)) paste0(p, "/") else ""
 }
 
+# Path to a file in the SOURCE tree (README.md, man/*.Rd, vignettes/*.Rmd),
+# or "" when it isn't there.
+#
+# Tests that assert on documentation content have to read the sources, and the
+# sources only exist when the suite runs from a checkout. Under R CMD check the
+# suite runs from the INSTALLED package, where man/ and vignettes/ are not
+# shipped and `../../README.md` does not resolve -- so those tests must skip
+# rather than error. CI runs testthat::test_local() from the checkout BEFORE
+# rcmdcheck, so the assertions are still enforced on every push; this only
+# stops them from failing a context that structurally cannot satisfy them.
+source_tree_path <- function(...) {
+  p <- testthat::test_path("..", "..", ...)
+  if (file.exists(p)) p else ""
+}
+
+# Skip unless every named source file is present (see source_tree_path()).
+skip_if_no_source_tree <- function(...) {
+  paths <- vapply(list(...), function(rel) do.call(source_tree_path, as.list(rel)),
+                  character(1))
+  missing <- vapply(paths, function(p) !nzchar(p), logical(1))
+  testthat::skip_if(
+    any(missing),
+    "package source tree not available (running against the installed package)"
+  )
+  invisible(paths)
+}
+
 # Skip a test if no corpus is reachable (bundled fixture or explicit remote URL).
 skip_if_no_corpus <- function() {
   p <- fixture_corpus_path()
diff --git a/tests/testthat/test-amount-units-documented.R b/tests/testthat/test-amount-units-documented.R
index 7d008cb..07d3d7d 100644
--- a/tests/testthat/test-amount-units-documented.R
+++ b/tests/testthat/test-amount-units-documented.R
@@ -18,16 +18,23 @@
 
 test_that("returned amounts are documented as full US dollars where readers meet the package", {
 
+  # README and vignettes ship only in the source tree, not in the installed
+  # package, so these assertions cannot run under R CMD check -- CI's earlier
+  # testthat::test_local() step is what enforces them. See
+  # skip_if_no_source_tree() in helper-fixture.R.
+  docs <- skip_if_no_source_tree(
+    "README.md",
+    c("vignettes", "total-spending.Rmd"),
+    c("vignettes", "population-denominators.Rmd")
+  )
+
   says_units <- function(path) {
     txt <- paste(readLines(path, warn = FALSE), collapse = " ")
     grepl("full US dollars|full U\\.S\\. dollars", txt, ignore.case = TRUE) &&
       grepl("\\$1,000s|thousands of dollars", txt, ignore.case = TRUE)
   }
 
-  expect_true(says_units(testthat::test_path("..", "..", "README.md")))
-  expect_true(says_units(testthat::test_path("..", "..", "vignettes", "total-spending.Rmd")))
-  expect_true(says_units(testthat::test_path("..", "..", "vignettes",
-                                             "population-denominators.Rmd")))
+  for (path in docs) expect_true(says_units(path))
 
   # Pin the documented claim to the actual behaviour, so the two cannot drift.
   # The expected raw amount is read straight from the corpus's parquet
diff --git a/tests/testthat/test-peer-summary-scope.R b/tests/testthat/test-peer-summary-scope.R
index 3746d1e..a4575a9 100644
--- a/tests/testthat/test-peer-summary-scope.R
+++ b/tests/testthat/test-peer-summary-scope.R
@@ -14,8 +14,15 @@
 
 test_that("cog_peer_compare() documents that summary_* rows are per-category quantiles", {
 
-  rd <- paste(readLines(testthat::test_path("..", "..", "man", "cog_peer_compare.Rd"),
-                        warn = FALSE), collapse = " ")
+  # man/ ships only in the source tree (the installed package carries a
+  # compiled help database instead), so the prose assertions below cannot run
+  # under R CMD check -- CI's earlier testthat::test_local() step enforces
+  # them. The numeric pin further down needs only the corpus, but it lives in
+  # the same test_that() as the sentence it protects, deliberately: they are
+  # one claim, and splitting them would let the prose drift while a separate
+  # test kept passing.
+  rd_path <- skip_if_no_source_tree(c("man", "cog_peer_compare.Rd"))
+  rd <- paste(readLines(rd_path, warn = FALSE), collapse = " ")
 
   # The @return section must say the quantile is computed within each cell...
   expect_match(rd, "within each|per-category|per category", ignore.case = TRUE)