eml: review of #173 - a lockfile for mailparser, the contents refusal speaks of files, the checker refuses what it cannot read

The reference tool job installs mailparser with npm ci from a committed
lockfile rather than resolving its tree each run. The refusal of contains
beside the attachment settings no longer calls a message an archive.
strict.py turns a header that is not UTF-8, a part with no Content-Type or
a date it cannot read into a refusal with a reason - four of six broken
messages ended in a traceback before. The reference tool guard runs its
cases side by side, 26.5 s down to 4.3 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: donislawdev

.github/mailparser/package-lock.json

@@ -0,0 +1,8 @@
+{
+  "name": "tfg-reference-mailparser",
+  "private": true,
+  "description": "mailparser for the eml reference tool guard, installed by the reference tools job with npm ci from the lockfile beside this file.",
+  "dependencies": {
+    "mailparser": "3.9.36"
+  }
+}

.github/mailparser/package.json

@@ -1376,11 +1376,16 @@ jobs:
           # Mail is read by mailparser beside Python's email package - the
           # parser much of the mail handling written in Node uses, and the one
           # that refuses a message of more than 1000 MIME entities
-          # (docs/EML-2026-10-07.md section 5.1). Pinned, installed outside the
-          # checkout, and named to the guard through TFG_MAILPARSER. Asked for
-          # its version, so a package that did not install stops this step, and
-          # the guard fails if it is named and reads nothing.
-          npm install --prefix "$RUNNER_TEMP/mailparser" mailparser@3.9.36
+          # (docs/EML-2026-10-07.md section 5.1). Installed with npm ci from the
+          # lockfile in .github/mailparser, so the whole tree is the one
+          # committed rather than whatever the registry resolves that day
+          # (review of #173), outside the checkout, and named to the guard
+          # through TFG_MAILPARSER. Asked for its version, so a package that did
+          # not install stops this step, and the guard fails if it is named and
+          # reads nothing.
+          mkdir -p "$RUNNER_TEMP/mailparser"
+          cp .github/mailparser/package.json .github/mailparser/package-lock.json "$RUNNER_TEMP/mailparser/"
+          npm ci --prefix "$RUNNER_TEMP/mailparser"
           echo "TFG_MAILPARSER=$RUNNER_TEMP/mailparser/node_modules/mailparser" >> "$GITHUB_ENV"
           node -e "console.log('mailparser', require(process.argv[1] + '/package.json').version)" "$RUNNER_TEMP/mailparser/node_modules/mailparser"