diff --git a/actions/docs-sync/docs-sync.sh b/actions/docs-sync/docs-sync.sh
index ba42647..3a9be9c 100644
--- a/actions/docs-sync/docs-sync.sh
+++ b/actions/docs-sync/docs-sync.sh
@@ -148,11 +148,32 @@ if [ -n "$source_dir" ]; then
 else
   # The repo is public: a plain tarball fetch, no auth, no git. Works for a
   # tag, a branch, or a commit SHA alike.
+  #
+  # THE FORGE COMES FROM THE ENVIRONMENT, NEVER FROM THIS FILE (#201).
+  # heavy-duty/ceremony exists on two forges and the same ref names a
+  # DIFFERENT TREE on each: `0.4.1` on this forge carries lib/forge.sh,
+  # lib/forge-github.sh and lib/forge-forgejo.sh; GitHub's `0.4.1` carries
+  # none of them. A hard-coded host therefore verified a consumer's mirror
+  # against a tree it never pinned — and did it with HTTP 200, so --check
+  # reported drift the consumer could not fix and --fix would have rewritten
+  # a correct mirror into the wrong one. The version numbers agreeing is the
+  # hazard, not the protection (#197 decision 2).
+  #
+  # GITHUB_SERVER_URL is what Actions injects on both forges, and
+  # lib/forge.sh already selects the whole backend on it — so a consumer run
+  # that reached this line has it. Unset means we do not know which forge the
+  # pin refers to, and guessing is what this issue is about: refuse instead,
+  # the same way the pin itself is never guessed.
+  [ -n "${GITHUB_SERVER_URL:-}" ] || die \
+    "docs-sync: GITHUB_SERVER_URL is unset, so the forge holding" \
+    "  heavy-duty/ceremony@$ref is unknown — and the same ref names a" \
+    "  different tree on each forge. Set it to the forge this consumer is" \
+    "  pinned against, or pass --source <dir>. This tool never guesses a forge."
   fetch_tmp="$(mktemp -d)"
-  url="https://github.com/heavy-duty/ceremony/archive/${ref}.tar.gz"
+  url="${GITHUB_SERVER_URL%/}/heavy-duty/ceremony/archive/${ref}.tar.gz"
   curl -fsSL "$url" | tar -xz --strip-components=1 -C "$fetch_tmp" || die \
     "docs-sync: cannot fetch heavy-duty/ceremony@$ref ($url) —" \
-    "  does the pinned ref exist?"
+    "  does the pinned ref exist on that forge?"
   src="$fetch_tmp"
   origin="heavy-duty/ceremony@$ref"
 fi
diff --git a/changelog.d/201.md b/changelog.d/201.md
new file mode 100644
index 0000000..c859f87
--- /dev/null
+++ b/changelog.d/201.md
@@ -0,0 +1,24 @@
+### Fixed
+
+- `actions/docs-sync` fetches the doctrine mirror from the forge named by
+  `GITHUB_SERVER_URL` instead of a hard-coded `github.com` (#201).
+
+- The same pin ref names a different tree on each forge, so a consumer's mirror
+  was verified against a tree it never pinned — and with HTTP 200, so `--check`
+  reported drift that could not be fixed (#201).
+
+- A fetch that cannot name its forge now refuses instead of guessing: no
+  `GITHUB_SERVER_URL` and no `--source` exits naming the variable, having
+  reached for no network (#201).
+
+- A failed fetch names the URL it actually tried, and asks whether the ref
+  exists on that forge rather than in the abstract (#201).
+
+### Added
+
+- `test/docs-sync.test.sh` drives the fetch path, which had no coverage at all:
+  every existing row passes `--source`, which overrides the fetch entirely
+  (#201).
+
+- A stubbed `curl` records the requested URL and serves a tarball, so which
+  forge a pin resolves against is a tested decision rather than plumbing (#201).
diff --git a/test/docs-sync.test.sh b/test/docs-sync.test.sh
index ff0f5b0..abec030 100644
--- a/test/docs-sync.test.sh
+++ b/test/docs-sync.test.sh
@@ -1,8 +1,9 @@
 #!/usr/bin/env bash
 # Contract tests for actions/docs-sync (issue #19). Constructed SOURCE trees
 # (a fake ceremony: manifest + docs) and CONSUMER trees (a release.yml
-# caller with the pin line), driven offline via --source — the fetch path
-# needs the network and is exercised by consumers, not here. The fake
+# caller with the pin line), driven offline via --source. The fetch path is
+# driven too, against a PATH-stubbed curl rather than the network (#201) —
+# which forge a pin resolves against is a decision, not plumbing. The fake
 # source's doc set is deliberately NOT the real five: a script that
 # hardcodes the vendored list instead of reading the manifest fails these
 # rows. set -u, not -e: failing commands are behavior for the harness to
@@ -299,4 +300,80 @@ check "unknown flag refused" 1 "unknown argument" \
 check "--source without a directory refused" 1 "no such directory" \
   in_consumer env-wired --check --source "$TMP/does-not-exist"
 
+# --- the fetch path: which forge, and never a guessed one (#201) ---------------
+
+# The fetch path had no coverage at all before this: every row above passes
+# --source, which overrides the fetch entirely, so the URL the tool actually
+# builds was asserted nowhere. It is asserted here with a PATH-stubbed curl
+# that records the URL and serves a tarball of the fake source tree — no
+# network, and the real tar pipeline still runs, so --strip-components stays
+# honest. CURL_FAIL makes the stub fail the way a missing ref does.
+FETCHBIN="$TMP/fetchbin"
+mkdir -p "$FETCHBIN"
+cat >"$FETCHBIN/curl" <<'STUB'
+#!/usr/bin/env bash
+printf '%s\n' "${!#}" >>"$CURL_URL_LOG"
+[ -z "${CURL_FAIL:-}" ] || exit 22
+exec tar -cz -C "$(dirname "$CURL_SRC")" "$(basename "$CURL_SRC")"
+STUB
+chmod +x "$FETCHBIN/curl"
+
+export CURL_URL_LOG="$TMP/curl-urls" CURL_SRC="$SRC"
+
+consumer fetched 0.4.1
+
+# fetch_sync <server-url> <args...> — the fetch path, no --source. Truncates
+# the URL log first so requested_url always answers about this run.
+fetch_sync() {
+  local server="$1"
+  shift
+  : >"$CURL_URL_LOG"
+  (cd "$TMP/fetched" && PATH="$FETCHBIN:$PATH" GITHUB_SERVER_URL="$server" \
+    bash "$SCRIPT" "$@")
+}
+requested_url() { cat "$CURL_URL_LOG"; }
+
+check "the fetch mirrors the pin fetched from the forge in the environment" 0 \
+  "added .ceremony/RULES.md" fetch_sync https://forgejo.example.test --fix
+check "...and the URL asked for names that forge, not a built-in one" 0 \
+  "https://forgejo.example.test/heavy-duty/ceremony/archive/0.4.1.tar.gz" \
+  requested_url
+
+# One pin ref, two forges, two trees — the whole reason #201 exists. The same
+# consumer must fetch from whichever forge it is running on.
+fetch_sync https://github.com --fix >/dev/null 2>&1
+check "the same pin on another forge fetches from that forge instead" 0 \
+  "https://github.com/heavy-duty/ceremony/archive/0.4.1.tar.gz" requested_url
+
+fetch_sync https://forgejo.example.test/ --fix >/dev/null 2>&1
+check "a trailing slash on the server URL does not double the separator" 0 \
+  "https://forgejo.example.test/heavy-duty/ceremony/archive/0.4.1.tar.gz" \
+  requested_url
+
+# Unset is not github.com. A tool that never guesses a ref must not guess a
+# forge either — and it must refuse BEFORE reaching for the network.
+no_server_sync() {
+  : >"$CURL_URL_LOG"
+  (cd "$TMP/fetched" && PATH="$FETCHBIN:$PATH" \
+    env -u GITHUB_SERVER_URL bash "$SCRIPT" --check)
+}
+check "no GITHUB_SERVER_URL and no --source → refuse, naming the variable" 1 \
+  "GITHUB_SERVER_URL is unset" no_server_sync
+check "...and the refusal says it never guesses a forge" 1 \
+  "never guesses a forge" no_server_sync
+nothing_fetched() { [ ! -s "$CURL_URL_LOG" ]; }
+check "...and nothing was fetched before refusing" 0 "" nothing_fetched
+
+# A ref that does not resolve on the forge in play: the message must name the
+# URL actually attempted, so "does the pinned ref exist" is answerable.
+fetch_fail() {
+  : >"$CURL_URL_LOG"
+  (cd "$TMP/fetched" && PATH="$FETCHBIN:$PATH" CURL_FAIL=1 \
+    GITHUB_SERVER_URL=https://forgejo.example.test bash "$SCRIPT" --check)
+}
+check "a failed fetch names the URL it tried" 1 \
+  "https://forgejo.example.test/heavy-duty/ceremony/archive/0.4.1.tar.gz" fetch_fail
+check "...and asks about the ref on that forge, not in the abstract" 1 \
+  "exist on that forge" fetch_fail
+
 summary