Replaces the binary acl.allow/deny model with five permission verbs
(r/w/c/d/a) and first-class roles, and adds an authenticated file API
(PUT/DELETE/POST move/mkdir) so the HTML tools can edit-in-place over
HTTP. Closes the AC-3(7) and AC-6 federal-readiness gaps.
File API (zddc/internal/handler/fileapi.go)
- PUT <new> → action c
- PUT <existing> → action w
- PUT <.zddc> → action a (CanEditZddc strict-ancestor rule)
- DELETE → action d
- POST mkdir → action c (auto-writes creator-owned .zddc when the
parent is Incoming/Working/Staging)
- POST move → action w on src + c on dst, atomic via os.Rename
- Optional If-Match for optimistic concurrency, --max-write-bytes cap,
audit log emits a structured file_write event per operation.
Permission model (zddc/internal/zddc/{acl,file,roles,cascade_mode}.go)
- acl.permissions: { principal → verb-set } map; principals are email
patterns or role names. Empty verb set is an explicit deny.
- roles: { name → members } definitions, available at the level they
declare and all descendants. Closer-to-leaf shadows ancestor.
- Legacy acl.allow/deny still work; they fold into permissions at
parse time (allow → "rwcd", deny → "").
- Cascade walks leaf→root; first level with any matching entry wins;
the union of matching verb sets at that level decides.
- --cascade-mode=strict adds a root→leaf ancestor-deny pre-pass so an
ancestor explicit-deny is absolute (NIST AC-6). Default delegated
preserves the existing commercial behavior.
Special folders (zddc/internal/zddc/special.go)
- Incoming / Working / Staging: mkdir auto-writes a .zddc into the new
subdir granting created_by + that email rwcda directly. Same form
operators write by hand; creator can edit it later to add others.
- Issued / Received: server-enforced WORM split. Cascade grants
inherited from above the WORM folder are masked to r only; grants
placed at-or-below the WORM folder retain r,c. Operators grant
write-once (cr) to the doc controller via an explicit .zddc at the
Issued/Received folder. Admins exempt — only escape hatch.
Browser polyfill (shared/zddc-source.js)
- HttpDirectoryHandle + HttpFileHandle implement the FS Access API
surface (values, getFileHandle, createWritable, removeEntry,
queryPermission/requestPermission) over zddc-server's listing JSON
and file API. Existing tools written against showDirectoryPicker
work unchanged.
- detectServerRoot() returns { handle, status }: tools auto-load on
HTTP, surface a clear "no permission to list" message on 403, and
fall back to the welcome screen on 0.
- classifier renames take the atomic POST move path on HTTP-backed
handles; mdedit and transmittal route reads/writes through the
polyfill so prior FS-API code paths cover both modes.
Tests
- zddc/internal/zddc/{cascade_mode,roles,special,acl}_test.go cover
delegated vs strict, role membership / shadowing / legacy fallback,
WORM split semantics, verb-set parser round-trip.
- zddc/internal/handler/fileapi_test.go now also covers role-based
vendor scenarios, WORM blocking vendor & doc controller writes,
explicit Issued .zddc unlocking the cr drop-box, admin bypass,
auto-ownership on mkdir, and strict-mode lockouts.
Docs
- ARCHITECTURE.md + zddc/README.md document the verb model, role
syntax, special-folder behaviors, cascade-mode flag, and full file
API surface. Federal-readiness gap analysis strikes AC-3(7) and
AC-6.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Ship a second parity-tested Rego policy that flips the cascade's
leaf-allow-overrides-parent-deny rule for NIST AC-6 conformance.
Standard cascade (existing access.rego, mirrors internal Go evaluator):
Bottom-up walk; first explicit match wins; deny-first within a level.
A leaf-level allow CAN override an ancestor's deny. This is the
cascade's intentional delegation property — a project-owner who
re-allows a previously-denied collaborator works as expected.
Federal mode (new access_federal.rego):
Any deny anywhere along the chain is absolute. An allow only matters
if no level (any depth) has denied the same email. Required by
NIST AC-6 default expectations: a central admin's deny at the root
must be unbypassable by a tenant who controls a subtree's .zddc.
Operators run real OPA with this Rego and point ZDDC_OPA_URL at it;
the internal Go evaluator stays on the commercial cascade. The
toggle is "which policy does your OPA evaluate," not a knob inside
zddc-server.
Surfaced via --print-rego flag:
zddc-server --print-rego # standard (default)
zddc-server --print-rego=standard # same
zddc-server --print-rego=federal # AC-6 strict variant
Parity test (federal_parity_test.go) compiles both Regos and asserts:
* They AGREE on every cascade scenario where no ancestor-deny
intersects a leaf-allow (most cases).
* They DISAGREE — by design — on the three scenarios where the
AC-6 rule differs:
- "leaf allows what parent denied" → standard allows, federal denies
- "deep leaf re-allows after middle deny" → same
- "glob deny at root + specific allow at leaf" → same
Cross-checks the divergence flag explicitly so any future change that
accidentally collapses the two policies fails the test.
Closes the AC-6 row of the federal-readiness gap analysis (now marked
"partially complete" in zddc/README.md — the full bullet would be a
built-in --policy-mode=federal toggle that also flips the in-process
Go evaluator).
Production binary unchanged at 13.1 MB (Rego files embedded as bytes;
OPA library remains test-only).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Phase 2 enhancements to the policy decider, plus listing-level ETags
that benefit every deployment regardless of decider mode.
Reference Rego policy
---------------------
internal/policy/rego/access.rego mirrors InternalDecider's semantics
exactly — bottom-up walk, deny-first within a level, default-deny when
HasAnyFile=true, glob matching with @-boundary semantics (special-cased
bare "*" because OPA's glob.match treats empty delimiters
inconsistently for that pattern).
Embedded into the binary via go:embed; --print-rego dumps it to stdout
so federal customers standing up an external OPA can use it as a
parity-tested baseline:
zddc-server --print-rego > /etc/opa/policies/zddc-access.rego
Parity test runner
------------------
parity_test.go imports the OPA Go module as a TEST-ONLY dependency
(github.com/open-policy-agent/opa@v0.70.0). Every fixture from the
internal Go evaluator's test set runs through both implementations;
any divergence fails CI. The test-only import means production
binaries (built by `go build ./cmd/zddc-server`) stay OPA-free —
release-flag binary size unchanged at ~13 MB.
The parity test caught a real bug on first run: bare "*" patterns
didn't match through OPA's glob.match with empty delimiters. Fixed
in access.rego with a special-case rule. This is exactly the kind of
subtle drift the parity guard exists to catch.
External-mode decision cache
----------------------------
HTTPDecider is now wrapped in a cachingDecider with a default 1s TTL.
Bursty patterns like .archive listings (one OPA round-trip per entry
before, one per (email, decision-input) tuple per TTL window after)
amortize cleanly. Verified: 20 identical /D/ requests produce 1 OPA
hit with cache, 40 hits without (each listing makes 2 ACL queries).
ZDDC_OPA_CACHE_TTL knob (default 1s) lets operators tune. 0 disables.
1s matches the fsnotify watcher debounce window — staleness is
bounded the same way other policy-edit propagation already is.
Internal mode unchanged; the in-process Go evaluator is already
cheaper than a cache lookup would be.
Listing ETags
-------------
GET / (project list) and GET /<dir>/ (directory listing JSON) now
carry content-hash ETag + Cache-Control: private, max-age=0,
must-revalidate. SHA-256 of the rendered JSON, truncated to 16 hex
chars (64 bits — collision risk on a listing of any realistic size
is vanishingly small).
Server-side caching deliberately not added: it would require
mtime-based invalidation, and Azure Files SMB mounts (a common
deployment substrate) don't support fsnotify reliably. The
content-hash ETag delivers the bandwidth savings (304 on identical
fetches) without depending on watcher correctness — the hash is the
actual response, so it can't lie about staleness regardless of
underlying watcher behavior.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Add an internal access-decision boundary that all handlers go through
instead of calling zddc.AllowedWithChain directly. Two implementations
ship:
* InternalDecider — wraps the existing zddc.AllowedWithChain. The
default. No new dependencies, identical semantics to the legacy
code path. ZDDC_OPA_URL=internal (or unset).
* HTTPDecider — POSTs the canonical OPA wire format
(POST /v1/data/zddc/access/allow with {"input": {...}}, response
{"result": true|false}) over HTTP, HTTPS, or a Unix-domain socket.
For federal customers running their own audited Rego policies
alongside zddc-server. ZDDC_OPA_URL=http(s)://… or unix:///….
External-mode failure semantics: unreachable / non-2xx / malformed
response → fail closed (deny) by default with a WARN log. Operators
who prefer availability over correctness flip with ZDDC_OPA_FAIL_OPEN=1.
The decider is constructed once at startup, plumbed through ACLMiddleware
into the request context. Handlers retrieve it via DeciderFromContext;
non-request callers (fs.ListDirectory, EnumerateProjects, enumerateAccess)
take it as an explicit parameter.
zddc.ZddcFile and zddc.ACLRules gain JSON tags so external Rego authors
get idiomatic input shape (acl.allow, admins, …) instead of Go field
names (ACL.Allow, Admins, …).
Test coverage:
* InternalDecider parity tests against zddc.AllowedWithChain (every
documented cascade scenario: empty chain, leaf-allow-wins, leaf-
deny-beats-parent, leaf-allows-what-parent-denies, deepest-match-
wins, etc.)
* HTTPDecider happy-path test (canonical wire format)
* Fail-closed / fail-open / malformed-response tests
Production binary size unchanged (no new deps; HTTP transport is
stdlib net/http). 11 ACL call sites migrated. End-to-end verified
against the worked-example layout in zddc/README.md.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
