Phase 4 Task 4.3+4.4 — docx Generator that produces a tracked Word
document by embedding template.docx and runtime-substituting the
HONEY_TRACK_URL placeholder in word/footer2.xml with the per-token
trigger URL. Preserves per-entry zip Method (STORE/DEFLATE) so
Word/LibreOffice still opens the result; non-footer entry bodies are
byte-identical to the template.
Generate returns {Kind: KindFile, Filename: t.Filename ?? "Document.docx",
Content: <patched zip>, ContentType: wordprocessingml MIME}. The
spec §9.3 reference snippet uses `t.Filename == ""` which won't
compile against the real schema — Token.Filename is *string. The
generator dereferences safely via resolveFilename, trimming and
falling back to the default for nil/empty/whitespace pointers.
Trigger mirrors webbug exactly per spec §9.3 line 1118: 200 + 43-byte
transparent GIF via pixel.Clone() + cache-control no-store + pragma
no-cache. Nil-token returns the same response with nil event
(spec §8.5 — no token-existence enumeration). realIP /
lastNonEmptyXFF / optionalHeader helpers are copied from webbug per
the standing rule (sanctioned duplication until Phase 9 middleware
extraction).
24 test cases including the six prescribed by implementation plan
§4.3 (OutputIsValidZip, FooterContainsTriggerURL,
FooterDoesNotContainPlaceholder, OtherEntriesUnchanged,
PreservesCompressionMethods, ReturnsGIFLikeWebbug) plus surrounding
correctness/regression coverage (type, kind, content type, filename
defaulting incl. whitespace, trigger-URL trailing-slash + subpath +
uniqueness, source-IP precedence with 9 subtests mirroring webbug,
GIF body independence per Trigger call, nil-token defense).
Also fixes pre-existing lint debt in cmd/builddocxtemplate from
commit f36cce9a: errcheck on the deferred f.Close (now propagates
via named return) and gosec G304 on os.OpenFile (now filepath.Clean
on the operator-supplied -out path). Rebuilding template.docx after
this change produces byte-identical output (verified via sha256sum).
82bb3a9f14