sandwich-hime/docs/SECURITY_EVIDENCE.md

Security evidence ledger

This ledger records what was actually inspected and executed. It is a maintainer-led self-assessment, not an independent audit, certification, formal verification, or guarantee that no vulnerability exists.

Assessment identity

Field	Value
Assessment date	2026-08-12
Public evidence identity	Exact file checksums in the co-published PUBLIC-SNAPSHOT.sha256; private/public commit mapping is retained only in the non-exported operational ledger
Assessment phases	Clean pre-remediation source followed by clean remediated source
Primary environment	Linux amd64 under WSL, Go 1.26.5
Declared minimum Go	Go 1.25
Assessor	Project maintainer with AI-assisted code review; human responsibility retained

Security remediation discovered during this assessment was committed and the named checks were rerun from a clean source state. Before this ledger can support a versioned release, the complete campaign must be rerun from the exact sanitized public release commit. Private-to-public commit mappings are retained outside the exported source rather than being disclosed here.

Observed evidence

Property examined	Enforcement or test surface	Result observed on 2026-08-12
Root correctness	go test -count=1 ./...	Pass
Concurrent access	go test -race -count=1 ./...	Pass
Runtime concurrency	(cd sando && go test -race -count=1 ./...)	Pass
Standard static analysis	go vet ./... and runtime equivalent	Pass
Reachable known vulnerabilities	govulncheck@v1.6.0 on both modules	No vulnerabilities found on 2026-08-12
Dependency surface	go list -m -json all in both modules	Zero third-party module requirements
Statement coverage	Go cover profiles on remediated source	compiler 75.2%; devserver 80.2%; runtime 96.6%
Parser robustness smoke	Two bounded Go fuzz targets	Pass; no panic found
Deterministic generation	repeated generate/check/hash/mtime gates	Pass
Writer failures	runtime error/short-write/nil-writer tests	Pass
HTML text/attribute/RCDATA escaping	compiler and runtime adversarial cases	Pass for enumerated cases
URL scheme handling	ordinary/trusted URL test matrix	Pass for enumerated cases
Filesystem boundaries	symlink, nested-module, VCS, ownership, stale-output tests	Pass for tested cases; see open findings
Development proxy browser boundary	Host, Origin, Fetch Metadata, CSP, fragment and response tests	Pass for tested cases
Native platform behavior	Linux execution; Windows/macOS cross-compilation	Native Windows/macOS execution not yet evidenced

Coverage measures statements executed by tests. It is not branch completeness and is not evidence that the executed behavior is secure.

govulncheck reports vulnerabilities known to the Go vulnerability database and reachable through its analysis. A clean result cannot detect unknown flaws, design errors, or vulnerabilities outside its model.

Security-relevant design evidence

Production boundary

The production sando module contains rendering contracts and contextual write helpers. It contains no HTTP server, router, middleware, template discovery, development proxy, plugin loader, or production process manager. Both compiler and runtime modules currently have no third-party Go module requirements.

Compiler behavior

Compilation builds and formats outputs in memory before generation writes. Recursive discovery rejects or skips observed symlinks, nested modules, VCS trees, vendor trees, and detected filesystem crossings. Existing non-owned, symlink, and non-regular output files are rejected. Each changed file uses an atomic replacement primitive; the whole set is not a filesystem transaction if a later replacement fails.

generate and check do not run project code, invoke the Go toolchain, fetch dependencies, or edit module metadata. himesan dev is intentionally separate: it builds and executes trusted project code and may fetch modules under the user's normal Go configuration.

Output contexts

The compiler accepts dynamic values only in its enumerated contexts. It rejects dynamic markup construction, unquoted attributes, event-handler values, dynamic style attributes, unsupported URL lists, foreign content, meta refresh, malformed tags, and unbalanced generated components. Runtime helpers escape ordinary text/attributes, validate ordinary whole-URL schemes before writing, and escape every trusted wrapper in RCDATA.

Script and style output require opaque trusted types. Those types deliberately move responsibility to trusted application code; they are not sanitizers.

Reproduction commands

Run from a clean canonical checkout. Networked scans contact the Go module proxy and vulnerability database.

go version
git status --short
git rev-parse HEAD^{commit} HEAD^{tree}

./scripts/check-licenses.sh
HIMESAN_RACE=1 ./scripts/verify.sh

go test -count=1 -cover ./...
(cd sando && go test -count=1 -cover ./...)

go run golang.org/x/vuln/cmd/govulncheck@v1.6.0 ./...
(cd sando && go run golang.org/x/vuln/cmd/govulncheck@v1.6.0 ./...)

go test ./internal/compiler -run '^$' \
  -fuzz '^FuzzCompileNeverPanics$' -fuzztime=20s
go test ./internal/compiler -run '^$' \
  -fuzz '^FuzzGoDelimiterNeverPanics$' -fuzztime=20s

The fuzz targets currently assert process robustness and result bounds. They do not yet prove semantic HTML safety.

Assessment findings and remediation status

The 2026-08-12 assessment identified six concrete gaps. Their current working-tree status is recorded here without rewriting the original baseline:

Finding	Current remediation	Executable evidence
Generated code named an ABI but did not enforce the exact contract	Generated code now requires the version-specific sando.ABISandoV1 symbol	TestGeneratedCodeRequiresVersionedRuntimeABIMarker; TestRuntimeABIMarker
Deleted or renamed sources could leave owned .sando.go orphans invisible to directory-level check	Directory discovery now reports owned outputs whose adjacent source is absent or non-regular and blocks the operation before writes	TestDirectoryOperationsRejectOrphanedOwnedOutputBeforeWrites
Component-context prose included arbitrary handwritten implementations in the generated-component guarantee	Runtime documentation, policy, and threat model now classify handwritten components as trusted output capabilities	API documentation plus policy review; generated-balance tests retain their narrower scope
An exited development child left its former upstream selected	Exit notification now clears only the matching active target immediately, independent of the watcher poll interval	TestClearTargetOnlyClearsSelectedUpstream; TestSupervisorClearsTargetWhenCurrentApplicationExits
Trusted-value warnings were described more broadly than their analysis supports	Policy and threat-model copy now call them best-effort lexical audit hints rather than type or taint analysis	Documentation assertion and review
Public copy implied a completed systematic html/template differential campaign	Policy and public security copy now describe fixed adversarial cases and list systematic differential work as open	Documentation assertion and review

The remediated clean source passed the race-enabled repository verifier, sanitized-snapshot tests, both bounded fuzz-smoke targets, compiler/runtime known-vulnerability scans, and Windows/macOS cross-compilation on 2026-08-12. Those results do not become release evidence until the changes are committed, exported to the sanitized canonical public tree, and re-run from that exact public commit. Native Windows/macOS execution and the other gaps below remain separate release decisions.

Open assurance gaps

• confidential mailbox delivery and response/recovery procedure must be tested;
• release signing, checksum, SBOM, and provenance rehearsal is incomplete;
• native Windows/macOS execution remains outstanding;
• browser-parser differential and semantic property testing need expansion;
• compiler input size, CPU, and memory have no built-in hard budget;
• filesystem checks do not defend against a hostile local actor racing path components between inspection and use;
• the watcher is a convenience mechanism, not a filesystem-integrity monitor;
• human-readable diagnostics can include hostile local filenames or child-tool output and should not be treated as a sanitized log protocol;
• development CSP rewriting is convenience, not production CSP validation;
• deliberately detached child descendants may evade process-tree cleanup;
• rendering has no built-in recursion, output-size, allocation, CPU, panic, or deadline enforcement;
• static cycle detection and trust-use warnings are best-effort analyses; and
• the project has no independent security audit or bug-bounty program.

Interpreting this ledger

“Pass” means the named command or case produced its expected result in the named environment on the assessment date. It does not mean “secure.” Confidence comes from keeping the boundary small, making risky capabilities explicit, preserving ordinary generated Go for review, publishing reproducible tests, recording failures, and correcting claims when evidence is weaker than the prose.