# AGENTS.md — ZDDC

## Commands

```bash
# ── ./build subcommands ────────────────────────────────────────────────────
# `./build` (no arg) is a source-side dev build only — assembles tool/dist/
# + cross-compiles zddc-server. dist/release-output/ and the live site are
# left alone. `./build beta` is an internal SHA snapshot for the BMC dev
# chart (no public artifacts). `./build release` is the canonical stable
# cut. Run `./deploy` to publish a stable cut.

./build                              # dev build (no release bundle)
./build beta                         # internal SHA snapshot for BMC dev chart
                                     #   (regenerates embedded/* + chore commit;
                                     #    no public artifacts in dist/release-output/)
./build release                      # coordinated stable cut, next version
                                     #   (tags all 8 artifacts at release commit)
./build release 1.2.0                # coordinated stable cut, explicit version
./build help

# ── ./deploy subcommands ────────────────────────────────────────────────────
# rsync the build output and content repo to /srv/zddc/ (Caddy's bind-mount).
# --delete-after — the live tree exactly mirrors source.

./deploy                             # full sync (content + releases)
./deploy --content                   # only ~/src/zddc-website/ → /srv/zddc/
./deploy --releases                  # only dist/release-output/ → /srv/zddc/releases/

# Single-tool dev build for testing (does NOT touch dist/release-output/):
sh tool/build.sh                     # archive|transmittal|classifier|landing|form|tables|browse

# Single-tool stable cut (rare; prefer ./build release so versions don't
# drift between tools).
sh tool/build.sh --release [<version>]

# Test all tools
npm test

# Test single tool
npx playwright test tool             # archive | transmittal | classifier | browse | form-safety | tables

# Dev server (cache-busting HTTP, on port 8000)
./dev-server start
./dev-server stop
```

No lint, typecheck, or format commands exist — the project is plain sh + vanilla JS.

Stable cuts seed `dist/release-output/` from the current
`/srv/zddc/releases/` — copying only immutable per-version files
(`<tool>_v<X.Y.Z>.html`, `zddc-server_v<X.Y.Z>_<plat>`) + their `.sig`
sidecars + `pubkey.pem`. The cut writes this version's per-version
file + canonical `<tool>.html` / `zddc-server_<plat>` symlinks on top.
`./deploy --releases` (rsync `--delete-after`) cleanses any stale
files in the live tree that this cut didn't include.

**Nothing is pushed automatically.** Run `./deploy` to publish; commit
+ push source changes to `main` separately.

## Architecture

Seven independent single-file HTML tools (`archive`, `transmittal`, `classifier`, `landing`, `form`, `tables`, `browse`). Each compiles to one self-contained `.html` in `dist/` with all CSS and JS inlined — most name their output `dist/tool.html`; `landing` writes `dist/index.html` (served at `/` by `zddc-server`). Tools share a small set of canonical helpers in `shared/` (filename parsing, ZDDC filter UI, theme, help) — see "Shared modules" below. `form` is the schema-driven renderer used by zddc-server's form-data system; `tables` is its read/aggregate counterpart, rendering a directory of YAML files as a sortable table whose rows click through to the form editor — discovered presence-based via `<name>.table.yaml` next to a sibling `<name>/` rows-dir (see "Form-data system" and "Tables system" below). `browse` is the file-tree navigator and also hosts the in-place markdown editor (`browse/js/preview-markdown.js`); the dedicated `mdedit/` tool has been retired.

```
tool/
  css/           source stylesheets (concatenated in order)
  js/            vanilla JS IIFEs (concatenated in order)
  template.html  placeholder markers: {{CSS_PLACEHOLDER}}, {{JS_PLACEHOLDER}}, {{BUILD_LABEL}}
  build.sh       assembles dist/tool.html
  dist/tool.html generated output — committed with `git add -f`

shared/
  base.css        CSS tokens and primitives included first by every tool's CSS build
  zddc.js         canonical filename/folder/revision parsers, formatters, status validation
  zddc-filter.js  shared ZDDC project/status filter UI module
  zddc-source.js  HTTP source abstraction — FS Access API polyfill (HttpDirectoryHandle,
                  HttpFileHandle) backed by zddc-server's listing JSON + file API
                  (PUT/DELETE/POST). Tools that auto-load the current dir in HTTP mode
                  call window.zddc.source.detectServerRoot() at init. The probe
                  returns { handle, status }: status 200 → use handle; 403 → user
                  lacks `r` on this directory (show "no permission to list"
                  message); 0 → not http(s) or non-zddc-server. Tools must
                  handle the 403 case so a permission-locked path doesn't
                  silently render as an empty welcome screen.
  hash.js         SHA-256 helpers used by the file API + classifier hashes
  theme.js        light/dark theme switcher
  help.js         shared help dialog module
  build-lib.sh    POSIX sh helpers (ensure_exists, concat_files, build_timestamp)
                  sourced by every tool's build.sh via: . "$root_dir/../shared/build-lib.sh"

# Hand-edited website content lives in a SEPARATE Codeberg repo
# (codeberg.org/VARASYS/ZDDC-website), typically cloned at
# ~/src/zddc-website/. Just content — no releases, no LFS:
#   index.html, reference.html, css/, js/, img/    hand-edited content
#   README.md, LICENSE                             repo housekeeping
#
# This repo's ./build produces a release bundle in dist/release-output/
# (gitignored, local-only). ./deploy rsyncs both into /srv/zddc/ on
# the deploy host (Caddy's bind-mount):
#   /srv/zddc/
#     index.html, reference.html, css/, js/, img/     ← from ~/src/zddc-website
#     releases/
#       index.html                        regenerated by `./build`
#       <tool>_v<X.Y.Z>.html              per-version (immutable)
#       <tool>_v<X.Y>.html  -> ...        symlink chain
#       <tool>.html         -> ...        canonical symlink → current stable
#       zddc-server_v<X.Y.Z>_<platform>   per-platform binary (raw bytes, no LFS)
#       zddc-server_<platform>            canonical per-platform symlink → current stable
#       zddc-server_<X>.html              stub page surfacing 4 platform DLs

helm/
  zddc-server-prod/  production-shaped Helm chart (compiles from source via init container)
  zddc-server-dev/   dev-shaped variant (tracks main HEAD; debug-level logging; faster probes)
  README.md          chart design rationale + quick-start
```

**Critical:** `dist/` files are gitignored. `tool/dist/<tool>.html` is the canonical built artifact for testing and the source for `--release` writes into `dist/release-output/`. `dist/release-output/` is the local-only release bundle. Neither is in git. Never edit them directly.

**Two-repo + deploy-host model.** Source code lives here (`codeberg.org/VARASYS/ZDDC`); hand-edited website content lives in a separate repo (`codeberg.org/VARASYS/ZDDC-website`, typically cloned at `~/src/zddc-website/`). The live site at `zddc.varasys.io` is `/srv/zddc/` on the deploy host (Caddy bind-mount), populated by `./deploy`. Release artifacts are NOT in git — they're produced by `./build release` into `dist/release-output/` and rsync'd to `/srv/zddc/releases/` by `./deploy --releases`. Each tool has exactly one canonical URL (`<tool>.html`, symlink → current stable) and a set of per-version immutable files (`<tool>_v<X.Y.Z>.html`). Same shape for zddc-server per platform. `shared/build-lib.sh` provides `promote_release` (HTML tools) and `promote_zddc_server` (binaries + matching stub pages); the top-level `./build` seeds per-version immutables from live state, then calls them in lockstep. Older releases are reproducible from any `<tool>-vX.Y.Z` tag in this repo (`git checkout zddc-server-v0.0.8 && ./build release 0.0.8`). No Codeberg release assets, no LFS.

## Shared CSS (`shared/base.css`)

Included as the **first** positional arg to every tool's `concat_files` CSS call. Provides:
- `:root` CSS custom properties — `--primary`, `--bg`, `--text`, `--border`, `--font`, etc.
- Brand color: `--primary: #2a5a8a` (matches zddc.varasys.io)
- Button primitive: `.btn`, `.btn-primary`, `.btn-secondary`, `.btn-sm`, `.btn-lg`, `.btn-link`
- `.app-header` + `.app-header__title` chrome rules
- `.build-timestamp`, `.hidden`, `.truncate`, webkit scrollbars

**Do not** define these in any tool's own CSS — they come from shared.

**Toast CSS** lives in `classifier/css/base.css` only (classifier is the only tool that uses toasts).

## Transmittal CSS quirks

- `transmittal/css/base.css` overrides `html { font-size: 16px }` inside `@media screen` — this must stay. `shared/base.css` sets `14px`; transmittal's floating labels are rem-based and were designed for 16px.
- The floating label position is defined in `transmittal/css/forms.css`, not Tailwind classes. If adding new Tailwind classes to `template.html`, add them to `transmittal/css/utilities.css` too — there is no Tailwind build step.

## Build system rules

- Every `build.sh` sources `shared/build-lib.sh` first (provides `ensure_exists`, `concat_files`, `build_timestamp`). Set `root_dir` before sourcing.
- Build scripts use **POSIX sh** (`#!/bin/sh` with `set -eu`), not bash.
- `concat_files` accepts **positional args only** (not array names).
- `awk` processes `template.html`, replacing `{{PLACEHOLDER}}` markers and stripping CDN `<script>`/`<link>` tags (pattern: `https?://`)
- `{{BUILD_LABEL}}` is substituted in all seven HTML tools via `gsub` in awk (use `gsub`, not `print` — the placeholder is inline in an HTML line). Value is `v<next>-dev · <ts> · <sha>[-dirty]` for plain dev builds, `v<next>-beta · <ts> · <sha>` for `./build beta` snapshot cuts, and `v<X.Y.Z>` for stable releases; computed before the awk step. The shared `is_red` flag controls whether the label is wrapped in a red+bold `<span>` (true for dev/beta, false for stable).
- Cleans up temp files via `trap cleanup EXIT`

**`</` escaping is mandatory.** Any JS containing `</tag>` inside string or template literals will break inline `<script>` embedding. Run:
```bash
sed 's#</#<\\/#g' "$input_js" > "$safe_js"
```
Required for any new tool with vendor JS or JS containing HTML template literals.

## JS module pattern

All JS is vanilla, no bundlers. Files are IIFEs, registered on `window.app.modules`. Load order = declaration order in `build.sh`. `window.app` is the only global.

```javascript
(function() {
    window.app.modules.mymodule = { ... };
})();
```

**Exception:** archive uses plain globals (`APP_STATE`, top-level functions) — not the IIFE/modules pattern.

**State values used inside event handlers must be read fresh from the source of truth, never captured at mount.** No bundler, no reactivity layer — closures don't get refreshed when the underlying state mutates. Cache the *node*, re-read the *bit* at click time:

```javascript
// Wrong — `writable` is whatever canSave returned at mount, even if
// the tree node's bit later flips to true (e.g. admin toggle reload
// re-fetched the listing).
var writable = canSave(node);
saveBtn.addEventListener('click', function () {
    if (!writable) return;       // STALE
});

// Right — re-read at click time.
saveBtn.addEventListener('click', function () {
    if (!canSave(node)) return;  // current
});
```

It's fine to use mount-time captures for *initial UI shape* (read-only banner, CodeMirror `readOnly:'nocursor'`, etc.) — those decisions are correct at the moment they're applied. The rule is specifically about gating logic in handlers that fire *after* mount.

This pattern bit twice in the markdown + YAML editors before we caught it: the typo `writable` (undefined) vs `writableMode` (captured) made every save click a no-op. Re-reading the source of truth would have surfaced the bug at click time instead of silently disabling save.

## ZDDC filename parsers

All parsing/formatting goes through `shared/zddc.js`, exposed as `window.zddc`. Tools call it directly — no per-tool wrappers.

`window.zddc` exports:
- `parseFilename(name)` → `{ trackingNumber, revision, status, title, extension, valid } | null` (extension WITHOUT leading dot)
- `parseFolder(name)` → `{ date, trackingNumber, status, title, valid } | null`
- `parseRevision(rev)` → `{ base, modifier, modifierType, modifierNumber, isDraft, modifierIsDraft, full }`
- `compareRevisions(a, b)` → number (canonical sort order)
- `formatFilename(parts)` / `formatFolder(parts)` — round-trips parsed output
- `isValidStatus(code)` — accepts known status codes plus `---`

All file objects across tools use `file.trackingNumber` (string) and `file.extension` (string, **no leading dot**, e.g. `'pdf'` not `'.pdf'`). When concatenating into a filename, write `name + '.' + ext`.

Coverage lives in `tests/zddc.spec.js` (47 cases). Add new edge cases there, not in tool tests.

## Testing quirks

- Playwright + Chromium only (File System Access API requirement)
- Tests open `dist/tool.html` via `file://` protocol — **always build before testing**
- File System Access API is mocked via `page.addInitScript()` using `tests/fixtures/mock-fs-api.js`
- Use `waitUntil: 'load'` or `'domcontentloaded'` not `'networkidle'` — bundled scripts keep the network "active"
- Archive's `#noDirectoryMessage` empty-state overlay is `position: absolute; top: 50px` — it must clear the header or it will block button clicks in tests

## ZDDC filename convention

Format: `trackingNumber_revision (status) - title.extension`

- `trackingNumber`: no spaces or underscores (e.g. `123456-EL-SPC-2623`)
- `revision`: `A`, `B`, `0`; draft prefix `~`; modifiers `+C1`, `+B1`, `+N1`, `+Q1`
- `status`: `IFA IFB IFC IFD IFI IFP IFR IFU REC RSA RSB RSC RSD RSI` or `---`
- Folder names prefix with date: `2025-10-31_trackingNumber (status) - title`

## Git workflow

- Feature-branch workflow; squash-merge feature branches to `main`
- Conventional commits: `feat(archive): ...`, `fix(transmittal): ...`
- Release tags: `<tool>-v<X.Y.Z>` per tool, all eight sharing the same X.Y.Z on a coordinated cut (e.g. `archive-v0.0.8`, `transmittal-v0.0.8`, `classifier-v0.0.8`, `landing-v0.0.8`, `form-v0.0.8`, `tables-v0.0.8`, `browse-v0.0.8`, `zddc-server-v0.0.8`)
- `dist/` is gitignored. Build artifacts (per-tool `dist/<tool>.html` and `dist/release-output/`) are NOT committed to this repo. Reproduce them from a tag with `./build release X.Y.Z`
- Hand-edited website content lives in a separate Codeberg repo (`codeberg.org/VARASYS/ZDDC-website`, cloned at `~/src/zddc-website/`). Source-code commits go to `main` here; content commits go to that repo
- Release artifacts live on the deploy host (`/srv/zddc/`), not in any git history. Use `./deploy` to publish

### Releasing — lockstep stable + beta snapshot

**Lockstep convention.** Every stable cut bumps all 8 artifacts (7 HTML tools + zddc-server) to the same version, even if a tool didn't change. Per-tool independent versions are gone. The coordinated next-stable target is `max(latest tag across all 8 tools) + 1` — `_coordinated_next_stable` in `shared/build-lib.sh`.

**No alpha or beta channels in the public release surface.** Simplified in May 2026 — channel mirrors (`_stable`, `_beta`, `_alpha`) and partial-version pins (`_v<X.Y>`, `_v<X>`) are gone. Each tool has exactly one canonical URL (`<tool>.html`, symlink → current stable) and a set of immutable per-version files (`<tool>_v<X.Y.Z>.html`). Same shape for zddc-server per platform.

**Storage model.** All release artifacts live on the deploy host at `/srv/zddc/releases/` (Caddy bind-mount, served as `https://zddc.varasys.io/releases/`). Locally they materialize in this repo's `dist/release-output/` (gitignored) when `./build release` runs; `./deploy` rsyncs them out. **No git history holds release artifacts** — older versions are reproducible from any `<tool>-vX.Y.Z` tag (`git checkout zddc-server-v0.0.8 && ./build release 0.0.8`). No Codeberg release assets, no LFS, no third-party mirrors.

| Artifact | Type | Layout |
|---|---|---|
| `<tool>_v<X.Y.Z>.html` | real, immutable | per-version HTML for each of archive, transmittal, classifier, landing, form, tables, browse |
| `<tool>.html` | symlink | canonical "current stable" URL per tool — always points at the latest cut's per-version file |
| `<tool>_v<X.Y.Z>.html.sig` | real, immutable | Ed25519 detached signature |
| `<tool>.html.sig` | symlink | canonical .sig URL (symlink → matching `.sig` of the symlinked target) |
| `zddc-server_v<X.Y.Z>_<platform>` | real binary | per-version cross-compiled binary, platform ∈ {linux-amd64, darwin-amd64, darwin-arm64, windows-amd64.exe} |
| `zddc-server_<platform>` | symlink | canonical "current stable" per platform |
| `zddc-server_v<X.Y.Z>_<platform>.sig` | real | matching detached signature |
| `zddc-server_<platform>.sig` | symlink | canonical .sig URL |
| `zddc-server.html` | generated stub | current-stable four-platform download page |
| `zddc-server_v<X.Y.Z>.html` | generated stub | per-version four-platform download page |
| `index.html` | regenerated by `build` | downloads landing page (version dropdown, tool cards, apps composer) |

**Single point of truth.** `./build release` is the canonical lockstep cut. It seeds `dist/release-output/` from `/srv/zddc/releases/` (only per-version immutables + `.sig` + `pubkey.pem`), forwards each HTML tool's build with the agreed version, calls `promote_zddc_server` (in `shared/build-lib.sh`) to copy the freshly cross-compiled binaries with their canonical symlinks, then `write_zddc_server_stubs_all` regenerates stub pages, then `sign_release_artifacts` produces `.sig` for every new per-version file, then `build_releases_index` rewrites the downloads page. **Then** the top-level build folds the regenerated `zddc/internal/apps/embedded/*` files into a `release: vX.Y.Z lockstep` commit and tags all 8 artifacts at that commit. `./deploy --releases` publishes the bundle.

- **Stable** (`./build release` or `--release X.Y.Z`): Writes per-version HTML for the seven HTML tools + per-version binaries for zddc-server (real bytes, immutable) + canonical `<tool>.html` and `zddc-server_<platform>` symlinks. Updates `zddc/internal/apps/embedded/*` to stable-labeled bytes, makes a release commit, tags all 8 (`<tool>-v<X.Y.Z>`) **at that commit** so binaries built from the tag embed clean stable bytes.
- **Beta** (`./build beta`): Internal SHA snapshot for the BMC dev chart pipeline. Regenerates `zddc/internal/apps/embedded/*` with beta-labeled bytes and makes a `chore(embedded): cut v<X.Y.Z>-beta` commit. **NO public artifact in `dist/release-output/`.** The chart's appVersion gets set to `"<X.Y.Z>-beta-<sha>"`; chart's Dockerfile parses the suffix and `git fetch`-es that SHA. The chart compiles its own binary from the fetched source — the binary's embedded HTML tools are whatever this commit wrote. No tag.
- **Plain dev builds** (`./build` with no arg): produce `tool/dist/<tool>.html` for HTML tools and `zddc/dist/zddc-server-<platform>` binaries; do NOT touch `dist/release-output/`, the live site, or `embedded/`. Use it to iterate without affecting deployable state.

**Bake-in invariant** — what zddc-server's binary embeds via `//go:embed` from `zddc/internal/apps/embedded/`:

| Image | Chart pin | Embeds |
|---|---|---|
| Prod (Dockerfile.prod, BMCD) | `appVersion: "X.Y.Z"` → tag `zddc-server-v<X.Y.Z>` | Stable-labeled bytes from the tagged release commit |
| Dev (Dockerfile) | `appVersion: "X.Y.Z"` or `"X.Y.Z-beta-<sha>"` → tag or SHA | Stable or beta-snapshot bytes (whichever the chart points at) |
| Local dev iteration | n/a | Use `tool/dist/<tool>.html` directly; binary's embedded copy lags |

On-page `{{BUILD_LABEL}}` format (HTML tools only — zddc-server's version comes from the binary itself):

- Plain dev: `vX.Y.Z-dev · <full-ts> · <sha>[-dirty]` (red), where X.Y.Z is the next-stable target.
- `./build beta`: `vX.Y.Z-beta · <full-ts> · <sha>` (red). Only seen on the dev chart's compiled binary.
- `./build release [X.Y.Z]`: `v<X.Y.Z>` (black).

After cutting a stable release, `git push origin main && git push origin --tags` to publish the new release commit + every per-tool tag in lockstep.

### Release discipline (MUST rules)

The build enforces lockstep mechanically (one command bumps all 8). The rules below are still on you.

1. **Stable doesn't regress.** No known-broken features that worked in the previous stable. If `v0.0.5` ships with a bug, the path forward is `v0.0.6` with a fix — never edit a previously-published per-version file in place. Per-version files are immutable.
2. **Lockstep is the contract.** Don't cut a single tool's stable without bumping the rest. The HTML tool's standalone `sh tool/build.sh --release X.Y.Z` flag still exists as an escape hatch but emits a tag that immediately drifts out of sync with the others.
3. **No backports.** Always cut a new stable at a higher version. Users pinned to an old version stay pinned by choice.
4. **Beta is internal.** Don't advertise `./build beta` snapshots to users — they're a BMC dev pipeline plumbing concept, not a "preview" release. The canonical URL `<tool>.html` always points at the latest stable.
5. **Hotfix path.** For critical bugs: fix on `main`, cut a new stable. Tag the commit message `fix:` or include "hotfix" so intent is visible in `git log`.
6. **Beta soak before promoting (recommended).** Give a beta-snapshotted build a few days on the dev chart before cutting the same code as stable. Not enforced; use judgment for trivial changes.

### Install model

No install script. Two paths:

- **Local** — download a tool `.html` from `https://zddc.varasys.io/releases/` and open it. Done.
- **Server** (`zddc-server`) — every tool is `//go:embed`'d into the binary at compile time (the current-stable build). Which tool a directory URL serves is driven by the `.zddc` cascade, not hardcoded: the baked-in baseline (`zddc/internal/zddc/defaults.zddc.yaml`, dumpable via `zddc-server show-defaults`) declares, via a recursive `paths:` tree, a `default_tool` (the no-slash form: `archive` at `archive/`, `transmittal` at `archive/<party>/staging/`, `browse` at `archive/<party>/{working,reviewing}/` (browse hosts the markdown editor), `classifier` at `archive/<party>/incoming/`, `tables` at `archive/<party>/{mdl,rsk}` and at the project-level `ssr/mdl/rsk` virtual rollups, `landing` at the deployment root) and `available_tools` (which tools may be auto-served / offered) per folder. **Project shape (May 2026 reshape):** `archive/` is the only physical project-root directory. Six top-level URLs are virtual aggregators: `ssr/mdl/rsk` (tables row-rollups across parties, with a synthesised `$party` source-party column the tables tool renders read-only and strips before write) and `working/staging/reviewing` (browse folder-nav listings of parties with non-empty content; per-party URLs 302-redirect to `archive/<party>/<slot>/`). Mkdir directly at the project root is restricted to `archive` and `_`/`.`-prefixed system names — virtual aggregator names and ad-hoc folders return 409. The trailing-slash form serves `dir_tool` (defaults to `browse`). See `internal/apps/availability.go` (`DefaultAppAt`, `AppAvailableAt`) and `internal/zddc/lookups.go` (`DefaultToolAt`, `DirToolAt`, `AvailableToolsAt`); the dispatcher chokepoint is `serveSpecializedNoSlash` in `cmd/zddc-server/main.go`. Where the cascade declares no tool, requesting `<app>.html` returns 404 like any other missing file. **The full canonical-folder convention (auto-own, WORM, virtual folders, standard roles) is documented in ARCHITECTURE.md § "Canonical folders, URL routing & the `.zddc` cascade".**

To override a tool's HTML (local-only — no fetch, no channels/versions):
1. Drop a real `<app>.html` file at the path → static handler serves it (highest priority).
2. Add an `<app>.html` member to the site bundle `<ZDDC_ROOT>/.zddc.zip` (a local zip read server-side via `internal/zipfs`; overrides that tool everywhere, and lets you add new `<name>.html` tools). To route a *different* tool at a path, change `default_tool` / `dir_tool` / `available_tools`.

Otherwise the embedded build-time copy is served. There is no `apps:` `.zddc` key, no upstream fetch, and no signature verification (all removed). `.zddc.zip` is config, not content: a direct `GET /.zddc.zip` is 404 for everyone; the server reads its members from the filesystem internally.

Operators audit by reading the `X-ZDDC-Source` response header: `bundle:<app>.html` / `embedded:<app>@<build>` (an on-disk override is served by the static handler with its own headers).

**Runtime mode detection** in archive is independent of install: it auto-detects multi-project / project-root / in-archive from `?projects=` plus folder shape. The other tools don't care where they live.

### Worktrees

Use `git worktree` to run multiple agents on separate branches simultaneously without filesystem collisions.

- Worktrees live at `~/src/zddc-<branch-name>` (sibling of the main clone)
- Before starting work on a feature branch, check `git worktree list`; if no worktree exists, create one: `git worktree add ~/src/zddc-<branch-name> -b <branch-name>`
- All edits, builds (`./build`), and tests (`npm test`) run from within the worktree directory — build scripts use relative paths so this works correctly
- The `dist/` force-commit rule (`git add -f`) applies per-worktree
- After the branch is merged, clean up: `git worktree remove ~/src/zddc-<branch-name>` then delete the branch
- Never run `git checkout` or `git switch` inside a worktree that another agent may be using

## Transmittal-specific

- Two-phase hydration: `populateStatic()` before publish, `hydrate()` on load of published file
- Reactive state via Proxy — `app.state.mode = 'view'` auto-notifies subscribers
- No runtime CDN loads. Every vendor library (jszip, docx-preview, xlsx, UTIF, Toast UI) is bundled at build time via `concat_files`. The dist HTML is fully self-contained — "ship the record player with the record."
- Published payload stored in `<script id="transmittal-data" type="application/json">`

## Markdown editor (inside browse)

The markdown editor lives at `browse/js/preview-markdown.js` and is mounted as the preview plugin for `.md`/`.markdown` files by `browse/js/preview.js`. The standalone `mdedit/` tool has been retired — `browse` is the editor.

- Toast UI Editor v3.2.2 is vendored at `shared/vendor/toastui-editor-all.min.js` and concatenated into `browse/dist/browse.html` at build time. No runtime CDN.
- YAML front matter (`---\n…\n---`) is split off on load and edited in a dedicated `<textarea>` in the sidebar; on save it's recombined onto the body. Always present (no "empty pane") so authoring new FM is a single click.
- In server mode (HTTP-backed file handles), three Download buttons appear in the file header — DOCX/HTML/PDF — fetching `?convert=<fmt>` and triggering a browser download. The buttons auto-save the dirty buffer first so the converted bytes reflect what's on screen.

## Server-side document conversion (`zddc/internal/convert`)

zddc-server can convert `.md` → DOCX/HTML/PDF on demand at `GET /<path>/foo.md?convert=docx|html|pdf`.

**Architecture.** zddc-server's Go code does the bare minimum: it `exec.Command("pandoc", args...)` or `exec.Command("chromium-browser", args...)`. **The sandbox + resource caps live in the IMAGE**, not in Go. In the production runtime image (`zddc/runtime.Containerfile`), `/usr/local/bin/pandoc` and `/usr/local/bin/chromium-browser` are symlinks to `zddc-sandbox-exec` — a shell wrapper that:

1. Creates a transient cgroup v2 (memory + pids cap from `ZDDC_CONV_MEM_MAX` / `ZDDC_CONV_PIDS_MAX` env), moves itself in.
2. Wraps the real binary at `/usr/bin/<name>` in a bubblewrap sandbox (`--unshare-all --unshare-user-try --die-with-parent --ro-bind /usr /usr ... --proc /proc --dev /dev --tmpfs /tmp --clearenv`).
3. exec's `/usr/bin/<name>` with the original argv.

Why this shape: swapping isolation strategies (firejail, systemd-nspawn, podman-run, raw exec for dev) is purely an image concern. The Go code never changed. A separate `zddc-cgroup-init` script runs at container start to delegate cgroup v2 `subtree_control` (the "no internal processes" constraint), then exec's zddc-server. Both scripts live in `zddc/runtime/`.

**Outer-container privileges.** Nested bwrap needs the outer container to permit user + mount namespace creation. Pod Security Standards defaults block this. The helm chart sets `securityContext: capabilities.add: [SYS_ADMIN]`, `seccompProfile.type: Unconfined`, `appArmorProfile.type: Unconfined`. Trade-off: a zddc-server RCE has near-root power within the container's namespace, but the bind-mount layout (overlay fs, no host /home or /usr visible) still bounds the blast radius. The per-conversion bwrap sandbox is the real isolation boundary between zddc-server and untrusted pandoc/chromium.

**Config knobs** (all in `cmd/zddc-server`):
- `--convert-pandoc-binary` (default `pandoc`) / `--convert-chromium-binary` (default `chromium-browser`; `chromium` on debian)
- `--convert-scratch-dir` (default `$TMPDIR`) — host scratch root; the wrapper bind-mounts the per-call subdir
- `--convert-mem-mib` (default 1024) → wrapper's `memory.max`
- `--convert-pids` (default 256) → wrapper's `pids.max`
- `--convert-timeout` (default 60s) → enforced in Go via `context.WithTimeout`

**Other plumbing.**
- I/O via stdin/stdout + scratch dir. Pandoc reads markdown from stdin, writes to stdout. Templates + intermediate HTML + output PDF live in a per-call subdir under the scratch root; the dir's host path is passed to the child via `ZDDC_SCRATCH` so the wrapper bind-mounts it into the sandbox at the same path (no path translation).
- Output cached at `<dir>/.converted/<base>.<ext>` (hidden by the `.` prefix). mtime synced to source so the fast path is a stat-and-serve with no exec. PUT/DELETE/MOVE on the source `.md` purges the sidecars.
- Per-project template variables (client/project/contractor/project_number) come from `.zddc` `convert:` cascade keys. Title/tracking_number/revision/status are derived from the filename via `zddc.ParseFilename`.
- **HTML/PDF templates** are named doctype files — `report`, `letter`, `specification` — plus shared partials (`_head.html`, `_doc.html`, `_scripts.html`), living in `pandoc/templates/` (single source of truth; `./build` mirrors them into `zddc/internal/convert/templates/` for `//go:embed`, guarded by `convert.TestEmbeddedTemplatesMatchSource`). A document picks one with `template: <name>` in its YAML front matter (default `report`) and turns on legal heading numbering with `numbering: true` (default off) — both flow straight from the front matter to the template, no converter code. The handler resolves overrides from the `.zddc.d/templates/<name>.html` cascade (`resolveTemplateSet` in `converttemplate.go`): a nearer level (`working/<party>/.zddc.d/templates/`) overrides a farther one (`working/.zddc.d/templates/`), which overrides the embedded default; an override may replace a doctype, a partial, or add a new doctype. NOTE: the per-doc converted cache keys on source mtime only, so editing a template override doesn't invalidate already-cached HTML — purge `.zddc.d/converted/` or touch the source to re-render.
- If pandoc/chromium aren't on PATH (operator running zddc-server outside the runtime image), the endpoint serves 503 with a Retry-After. The rest of the server keeps working. Operators who run zddc-server with raw pandoc/chromium (no wrapper) get a working but unsandboxed conversion endpoint — useful for dev iteration.

## Form-data system (`form/` + zddc-server form handler)

A schema-driven form renderer used to collect structured data into YAML files in the file tree. The form tool (`form/`) is the renderer; the server-side endpoints live in `zddc/internal/handler/formhandler.go`; the validator is `zddc/internal/jsonschema/`.

**Form spec**: `<name>.form.yaml` — top-level envelope is `{title, description, schema, ui, mode}`. `schema` is JSON Schema 2020-12 (subset; see "Validator subset" below). `ui` is RJSF-style (`ui:widget`, `ui:order`, `ui:autofocus`, `ui:placeholder`, `ui:help`, `ui:readonly`, `ui:options.{addable,removable}`). LLMs author this dialect well.

**URL conventions** (form posts back to its own URL; server strips `.html`). The spec lives **inside** the rows-dir alongside the row YAMLs, so the whole form (spec + every submission) is a single self-contained directory:
- `GET  /<dir>/form.html` — render empty form
- `POST /<dir>/form.html` — create new submission → 201 + Location capability URL pointing at the new `<dir>/<id>.yaml`
- `GET  /<dir>/<id>.yaml.html` — render form pre-filled from `<id>.yaml`
- `POST /<dir>/<id>.yaml.html` — overwrite that submission → 200

**Storage**: spec at `<dir>/form.yaml`. Submission filenames depend on whether the directory has a cascade-declared `records:` rule (see "Records, audit, and history" below):
- **No matching `records:` rule** — submissions land at `<dir>/<YYYY-MM-DD>-<email-sanitized>.yaml` (the legacy date+email scheme; still the path for ad-hoc operator-defined forms).
- **Matching `records:` rule** (mdl/rsk/ssr and operator-declared records) — filename is composed from body fields via the rule's `filename_format`; for rsk-style rules the server also auto-assigns a per-row sequence within the table-scope group.

Copying `<dir>` elsewhere copies the spec plus every submission together. ACL applies via the existing `.zddc` cascade.

**Round-trip**: v0 is form-as-truth — submission YAML is regenerated from form state on every save; comments in submissions are not preserved. File-as-truth mode (lossless YAML round-trip via the eemeli/yaml Document API) is a v1 feature, needed for hand-edited files like `.zddc` itself.

**Validator subset** (`zddc/internal/jsonschema/`): `type` (string/number/integer/boolean/array/object), `enum`, `minimum`, `maximum`, `minLength`, `maxLength`, `pattern`, `required`, `additionalProperties: false`, `properties`, `items`, `format` (`date`, `email`). Schema also carries three client-facing extensions that survive round-trip but aren't enforced by the validator (the server enforces them via cascade or strip-on-write): `readOnly: true` (UI renders disabled), `x-labels: { code → label }` (paired display text for enum dropdowns). NOT supported in v0: `$ref`, `$defs`, `if/then/else`, `oneOf`/`anyOf`/`allOf`, conditional visibility. The form-spec meta-schema enforces that authors stay in the supported subset.

**Renderer subset** (`form/js/`): types listed above, enum (select / `ui:widget: radio`), `format: date|email`, textarea, nested objects, arrays of primitives, arrays of objects with add/remove rows. `ui:show-when` and reorder are v1.

**Adding a new form**: create a directory `<dir>/` and drop `form.yaml` into it (per `.zddc` ACL). No code change required. Visit `<dir>/form.html`.

## Tables system (`tables/` + zddc-server table handler)

Read/aggregate counterpart to the form system. Renders a directory of YAML row files as a sortable, filterable table; each row clicks through to its `<id>.yaml.html` form editor. The tables tool (`tables/`) is the renderer; the server-side recognizer is `zddc/internal/handler/tablehandler.go RecognizeTableRequest`.

**Discovery is presence-based**, the same convention as forms: a `<dir>/table.yaml` on disk auto-mounts at `<dir>/table.html`. The directory is the table.

**Storage** (self-contained directory):

```
<dir>/
  table.yaml         ← spec
  form.yaml          ← row-edit form (paired with table.yaml)
  <id>.yaml ...      ← rows
```

`table.yaml` and `form.yaml` are excluded from the rows list. Each row is also a form submission — the same files the form system reads — so the table view and the per-row form editor are two views of one folder of YAMLs. Copying `<dir>/` elsewhere copies the entire table (spec + form + every row) — that's the whole point of the in-dir layout.

**One table per directory** by construction (the spec is the singleton `table.yaml`). No `.zddc` reference needed; presence-based discovery is the entire rule. To make a directory a table, drop a `table.yaml` in it — that's it.

**Subfolders inside a table dir are allowed and silently ignored as rows.** The rows iterator filters non-`.yaml` entries, so directories don't show up in the table view. Legitimate subfolder use cases:
- **Nested sub-tables** — `<dir>/sub-list/table.yaml` is its own self-contained table at `<dir>/sub-list/table.html`. Composition, not violation.
- **Per-row attachments** — `<dir>/<id>.attachments/file.pdf`. Natural sidecar pattern; the row YAML can reference its attachments by relative path.
- **Drafts / staging** — `<dir>/.drafts/<id>.yaml` (dot-prefix → hidden from listings as well as from the table).
- **Per-row history** — `<dir>/.zddc.d/history/<base-without-ext>/<RFC3339Nano>-<sha8>.yaml`. Server-managed; one directory per record, one file per archived revision. See "Records, audit, and history" below.

**Default-MDL fallback at `archive/<party>/mdl/`**: when no `table.yaml` (or `form.yaml`) exists on disk in this exact location, the server serves embedded default bytes. The `mdl/` directory itself doesn't even need to exist — the URL renders the default MDL view fully virtually so a fresh archive surfaces the master document list without operator setup. Outside `archive/<party>/mdl/`, presence-based discovery is the rule.

**Default-MDL columns mirror the tracking-number components** documented at `zddc.varasys.io/reference.html#tracking-numbers`. The default ships the five required components + an optional per-deliverable `suffix`: `originator`, `project`, `discipline`, `type`, `sequence`, `suffix` — each a slot of the deliverable's permanent identifier — plus `title`, `plannedRevision`, `plannedDate`, `status`, `owner`. The project-wide `phase` / `area` components are shipped only as commented-out templates in the default form/table YAML (a project that uses them must enable them on *every* deliverable to keep filenames lexically consistent, so the simplest default omits them). `originator` is **folder-bound**: the cascade's `folder_fields` pins it to the party-folder name, so the form renders it read-only and the server sets it from the path. The form schema accepts free-text on every other component by default; projects narrow the vocabulary via the cascade's `field_codes:` (see below). Operator overrides at `archive/<party>/mdl/{table,form}.yaml` still win atomically over the embedded defaults. Source: `zddc/internal/handler/default-mdl.{table,form}.yaml`.

**Adding a new table**: create a directory `<dir>/` and drop `table.yaml` (and optionally `form.yaml` for row editing) into it. No code change required. Visit `<dir>/table.html`.

## Records, audit, and history

The "records" subset of the tables system carries three guarantees the generic form/table flow doesn't: server-stamped audit fields, immutable per-record history, and cascade-driven filename composition. The mechanism lives in `zddc/internal/handler/history.go` (`WriteWithHistory`) and `zddc/internal/zddc/field_codes.go`. Three record types ship out of the box:

| Type | Folder | Filename | Identity carrier |
|---|---|---|---|
| **MDL** (deliverables) | `archive/<party>/mdl/` (many siblings) | Composed tracking number, e.g. `ACM-PRJ-EL-SPC-0001.yaml` | Body's component fields |
| **RSK** (risk register) | `archive/<party>/rsk/` (many siblings, multiple tables) | `<table-tracking>-<row>.yaml`, e.g. `ACM-PRJ-EL-RSK-0001-001.yaml` | Body's components + server-assigned row sequence |
| **SSR** (parties register) | `archive/<party>/ssr.yaml` (one per party folder) | Always literal `ssr.yaml` | Parent folder name (existing `name` strip/inject in `ssrhandler.go`) |

**Two new `.zddc` keys** carry the rules (see `zddc/internal/zddc/file.go` + `field_codes.go`):

- `field_codes:` — vocabulary for the components used in filename composition and constrained body fields. Each entry is a discriminated union over `kind: enum|pattern|free` (`{kind: enum, codes: {ACM: Acme Inc, …}}` / `{kind: pattern, pattern: "^[0-9]{4}$"}` / `{kind: free, description: "..."}`). Map-merge across the cascade (like `display:`/`tables:`) — a deeper level can narrow or replace a single code's vocabulary without dropping unrelated codes.
- `records:` — per-pattern rules keyed by filename basename (literal `ssr.yaml` or glob `*.yaml`). Each entry carries `filename_format` (composition template with `{field}` and `{field?}` placeholders), `field_defaults`, `locked`, `folder_fields`, plus `row_field` + `row_scope_fields` for RSK-style tables-of-rows. Filename-pattern scoping is what lets the SSR rule live at the party-folder level without affecting `mdl/`, `rsk/`, `received/`, etc., siblings.
  - `folder_fields:` — map of `field → parent-distance` that binds a body field to an ancestor folder name (the folder is the sole source of truth). The map value is how many directories ABOVE the record's own directory the source folder sits (`originator: 1` under `archive/<party>/mdl/` resolves to the `<party>` folder). The server overwrites the body field with the derived name before validation + composition (so a client value can never disagree; a mismatched URL still trips the `filename_format` check), and the form renderer marks the field read-only and pre-fills it.

Defaults are baked into `defaults.zddc.yaml`; `field_codes:` ships empty (every deployment writes its own vocabulary). The default mdl/rsk records bind `originator` via `folder_fields: {originator: 1}` so the party folder is the originator's source of truth — `originator` is therefore *not* a `field_codes:` entry by default.

**Six server-managed audit fields** are injected on every write and stripped from incoming bodies before validation (snake_case to match `.zddc`'s existing `created_by:`):
- `created_at`, `created_by` — stamped on create; preserved untouched on every update
- `updated_at`, `updated_by` — refreshed on every write
- `revision` — `1` on create, `+1` per update
- `previous_sha` — first 8 hex chars of SHA-256 of the prior revision's bytes; absent on create. Forms a hash chain for tamper evidence

**History layout**: for any record at `<dir>/<base>.<ext>`, the prior version is archived at `<dir>/.zddc.d/history/<base>/<RFC3339Nano-UTC>-<sha8>.<ext>` before the live file is overwritten. Per-record subfolder under `.zddc.d/history/` keeps `readdir` cheap and makes party-folder rename move SSR history along atomically (the dot-folder is inside the party folder, so `os.Rename` carries it).

**Write ordering**: history first, then live. A crash between the two leaves the prior version safely archived; the retry is idempotent because the history filename is deterministic (timestamp + sha of prior bytes).

**Strip-and-stamp policy**: clients can't forge audit fields. `WriteWithHistory` strips all six keys from the incoming body BEFORE schema validation runs, then injects authoritative values from request context. A client that sends `created_by: eve@evil` finds it silently overwritten with the request principal.

**Wire surface** — every record-write entry point converges on `WriteWithHistory`:
- `PUT /<record>.yaml` — routed through `WriteWithHistory` automatically when the basename matches a `records:` rule. Response echoes the stamped YAML as the body (Content-Type: application/yaml) so the tables client can update its row state without a re-GET.
- `POST /<dir>/form.html` (in-dir create) and `POST /<dir>/<id>.yaml.html` (in-dir update), plus the project rollup `POST /<project>/(mdl|rsk)/form.html` — when a `records:` rule with a `filename_format` applies in the target directory, these compose the filename (shared `recordCreatePrep`: field_defaults + folder_fields + row-assign + compose), then route through `WriteWithHistory` for audit + history + the composed-name match check. So "+ Add row" from a per-party table no longer drops un-stamped, date+email-named rows. Directories with no record rule keep the generic date+email submission write.
- `GET /<record>.yaml?history=1` — JSON list of prior revisions: `[{revision, ts, by, sha, path}, …]`. ACL gates against the live record (read it → read its history).

**Record-vs-config distinction**: `WriteWithHistory` fires only for genuine record paths. The gate (`isRecordPath` in `fileapi.go`) excludes `table.yaml`, `form.yaml`, `.zddc`, and the spec naming variants `*.table.yaml` / `*.form.yaml`. Those bypass audit stamping (they're configuration, not data) and go through plain `WriteAtomic`.

**Operator customization**:
- To narrow a deployment's discipline codes: write `field_codes: discipline: {kind: enum, codes: {EL: Electrical, ME: Mechanical, …}}` at the project root `.zddc`. (`originator` is folder-bound by default — see `folder_fields` above — so it's set from the party folder rather than constrained by a code list.)
- To add a new table type: declare a `records:` entry under the appropriate `paths:` level (or a sibling `.zddc` in the folder) with a `filename_format` referencing fields the body carries.
- To inspect a record's revision history: `curl https://<host>/<path>.yaml?history=1 -H 'Authorization: Bearer …'`.

**Server-side only (offline gap)**: every record guarantee — audit stamping, immutable history, `filename_format` composition, `field_codes`/`locked` validation, and `folder_fields` binding — runs in zddc-server (`WriteWithHistory` + the form handlers). The tools opened offline (`file://` or the File-System-Access picker, no server) **cannot** enforce any of it: a record write needs the server. This is by design — the server is the authority — but it means folder-bound originator, composed filenames, and audit fields don't materialize for purely-offline edits.

**Upgrading a pre-folder-binding deployment** (records created before these defaults):
- Stored `suffix:` values that carried a leading dash under the old `-A` convention now compose a doubled dash (`…0001--A`) and 422 on next edit. Strip the leading dash from `suffix:` values (`-A` → `A`); the cascade's `filename_format` supplies the separator now.
- A row whose `originator` differs from its party-folder name is silently rewritten to the folder name on the next write (the folder is the source of truth). Filenames whose originator segment disagrees with the folder will 422 until the file is renamed to match.
- Deployments that used the project-wide `phase`/`area` components already supplied a custom `form.yaml` + `.zddc` override (the prior default couldn't compose those slots otherwise), so the phase/area removal from the embedded defaults doesn't affect them.

Source: `zddc/internal/handler/history.go`, `zddc/internal/zddc/field_codes.go`, `zddc/internal/zddc/walker.go`, `zddc/internal/zddc/cascade.go`, `zddc/internal/zddc/defaults.zddc.yaml`. Tests: `zddc/internal/handler/history_test.go`, `zddc/internal/zddc/field_codes_test.go`.

## Implementation-vs-dependency policy

Match implementation cost to actual surface used. Reimplement focused subsets when a dep's surface area is much larger than what we consume; adopt for genuinely large specs (YAML parsing, etc.) where reimplementing is foolish. Examples in this codebase:

- **`zddc/internal/jsonschema/`** — focused 2020-12 validator (~300 LoC) covering only the v0 form-spec subset. A full library (e.g. `santhosh-tekuri/jsonschema/v6`) brings 70%+ surface we don't use.
- **`gopkg.in/yaml.v3`** — adopted as a dep. Reimplementing YAML is foolish.

This is a guideline, not a rule. Revisit per-feature: when v1+ form-spec adds `$ref` + `oneOf` + `if/then/else`, the validator's "savings" evaporate and adopting becomes cheaper.

## zddc-server

Go HTTP server sub-project living at `zddc/`. Replaces `caddy file-server --browse` for ZDDC archives.

### Bootstrap config (REQUIRED — unlocks the server)

zddc-server grants no access to anyone until two operator files are populated. The embedded `defaults.zddc.yaml` ships with empty role members and references those roles throughout its cascade, so a fresh deployment refuses every request until the operator opts in. `zddc-server` logs a startup warning (see `warnIfNoBootstrap` in `zddc/cmd/zddc-server/main.go`) when the root `.zddc` grants nobody anything — skipped under `--no-auth`.

**Root `<ZDDC_ROOT>/.zddc`** — at minimum, declare an admin:

```yaml
admins:
  - cwitt@burnsmcd.com
```

`admins:` is honored only at the root (subdir admins are read but ignored by `IsAdmin`, see `zddc/internal/zddc/file.go:109-112`). Admins are sudo-style — powers gate on the `zddc-elevate=1` cookie or implicit bearer-token elevation.

**Per-project `<project>/.zddc`** — populate role members:

```yaml
title: "Project Phoenix"
roles:
  document_controller:
    members:
      - dc1@burnsmcd.com
  project_team:
    members:
      - alice@burnsmcd.com
      - '*@acme.com'
  observer:
    members:
      - auditor@regulator.gov
```

The embedded cascade already grants `project_team: r` and `observer: r` project-wide, and `document_controller: rw` (+ `rwc` on `archive/`, WORM filing on `received/issued`, `rwcd` at `incoming/` and `staging/` for the QC + transfer workflows). When DC creates an `archive/<party>/` folder the auto-own `.zddc` written there grants both their email AND the `document_controller` role `rwcda` (via `auto_own_roles: [document_controller]` in the defaults) — so any peer DC has full authority at every party without needing subtree-admin status. Plan-Review approval is part of the `document_controller` role by design — there is no separate `approver` role; two-person sign-off, when needed, is expressed via per-folder `.zddc` overrides. The three standard roles' invariants are locked down in `zddc/internal/zddc/standardroles_test.go`.

The in-flight lifecycle slots form a one-way ratchet:

  `working/` → `staging/` → `issued/` (WORM)

Each handoff drops `project_team`'s modify rights for the slot they pushed from. At `working/` they have `cr` plus `rwcda` inside their auto-own-fenced `<email>/` home. At `staging/` they have `cr` only (drop files, no modify after). DC takes over with `rwcd` at staging and files to `issued/` via the WORM `cr` grant. Same shape on the inbound side via `incoming/` → `received/` (WORM).

Pick a role per persona:

- `document_controller` — per-party records custodian; files into WORM `received/issued`, manages the `working/staging/reviewing` lifecycle, QCs the counterparty's drops in `incoming/`. **NOT a subtree-admin** anywhere — authority comes purely from cascade grants (the role-level `rwcda` written by `auto_own_roles` at each party, plus explicit `rwcd` at `incoming/` and `staging/`). They cannot bypass WORM (only worm-create via the list) or reach inside fenced working homes.
- `project_team` — day-to-day contributor. Reads across the project; ratchets through the in-flight slots. Owns their `archive/<party>/working/<email>/` home via auto-own with a fenced `.zddc` (`inherit: false`).
- `observer` — pure read-only across the project. No auto-own home (the role itself has no `c` anywhere). Intended for auditors, regulators, and external read-only viewers who must not contribute content.

**Roles overlap on purpose.** DCs are typically internal employees and ARE in `project_team` (often defined as `*@example.com`). The cascade is "deepest level that has any matching principal wins for that level, with within-level UNION of all matched principals". To prevent a `project_team: cr` grant at the slot from shadowing a DC's role-level `rwcda` inherited from the party folder, the embedded defaults RESTATE `document_controller: rwcda` at every slot that has a project_team-specific grant (`working/`, `staging/`, `reviewing/`). Within-level union → DC gets `rwcda` ∪ `cr` = `rwcda`. Operators adding new slot-level project_team grants in their own `.zddc` files should follow the same pattern. (Internal `observer` users matched by the project_team wildcard would still be lifted to `cr` by the union — observer is intended for EXTERNAL auditors whose emails don't match the wildcard. Deployments with internal observers should use explicit project_team membership instead of a wildcard.)

**Schema** (source of truth: `zddc/internal/zddc/file.go:43-49`, `:74-77`, `:139-145`):

- `acl: { permissions: { <principal>: <bits> }, inherit: <bool>? }` — there is no `allow:` key; an `allow:` block parses cleanly but is silently dropped during unmarshal. Real footgun — easy to write `acl: { allow: [...] }` and assume it works.
- Bits: any subset of `r w c d a` (read / write / create / delete / admin); empty string is an explicit deny.
- Principals: email (must contain `@`), glob (`*@domain.com`), or role name (no `@`).
- `roles: { <name>: { members: [...], reset: <bool>? } }` — members union across the cascade unless `reset: true`.
- `admins: [<email>, ...]` — root only; sudo-style elevation per request.
- `auto_own: <bool>` — when true, ensure.go writes a `.zddc` granting the creator's email `rwcda` on first mkdir.
- `auto_own_fenced: <bool>` — adds `inherit: false` to the auto-own `.zddc` (private-by-default home). No effect without `auto_own: true`.
- `auto_own_roles: [<role>, ...]` — additional role names that get `rwcda` in the auto-own `.zddc`, alongside the creator's email. Lets the schema express role-level peer authority without `admins:` (which would be subtree-admin and bypass WORM/fences via elevation).
- `title:` — read only from the per-project `.zddc`; surfaces on the landing-page picker.

**Two `inherit` scopes, one word.** `ZddcFile.Inherit` (top-level) drops the embedded baseline AND fences ancestor on-disk `.zddc` files from this point of the cascade. `ACLRules.Inherit` (nested under `acl:`) is narrower — it only fences ACL evaluation; embedded roles, paths-tree contributions, WORM lists, and other non-ACL keys still cascade through. Concretely:

- To opt out of embedded defaults at deployment, set `inherit: false` at the root `<ZDDC_ROOT>/.zddc` (top-level).
- To make a per-user home private (block ancestor read grants) but keep cascade-derived behaviour like default_tool, set `acl: { inherit: false }`. The auto-own-fenced mechanism uses this form.

These are NOT interchangeable. A note about which one operators want lives in `cascade.go:13-21` (the `PolicyChain` doc) and the relevant struct fields in `file.go`.

Run `zddc-server show-defaults` to dump the embedded `defaults.zddc.yaml` with annotated comments — that's the full schema with all the cascade keys (`worm:`, `auto_own:`, `drop_target:`, `convert:`, `on_plan_review:`, `records:`, `available_tools:`, `default_tool:`, `dir_tool:`, etc.).

### Build

zddc-server ships as a cross-compiled binary, not a container image. There's no Containerfile or compose file in this repo (the chart Dockerfiles compile from source at deploy time at the right tag).

```sh
# Compile a local binary for the host platform via the build image.
# Same flag pattern as Test below — see that subsection for why.
podman run --rm --network=host -v "$PWD":/src:Z -v /tmp/gocache:/root/go/pkg/mod:Z \
  -w /src/zddc -e GOPROXY=https://proxy.golang.org -e GOSUMDB=off -e GOPRIVATE= \
  localhost/zddc-go:1.24 go build -o zddc-server ./cmd/zddc-server

# `go run` is normally a one-liner but in-container `go run` of a network
# server is awkward — for dev iteration, build with the line above and
# launch the binary on the host (`./zddc/zddc-server`).
```

The repo's top-level `./build` cross-compiles the four release binaries (linux/amd64, darwin/amd64, darwin/arm64, windows/amd64) into `zddc/dist/` via a containerized Go toolchain (podman or docker). On `./build release` it also promotes those binaries to `dist/release-output/` with their per-platform canonical symlinks + stub pages — same lockstep flow as the HTML tools. `./deploy` rsyncs the bundle to `/srv/zddc/releases/`.

### Test

Go is **not** installed on the dev shell host directly — run `go test` (and `go build`) through a golang-alpine image. `./build`'s containerized cross-compile already pulls `golang:1.24-alpine` as a build stage; tag it for reuse:

```sh
# One-time: locate the golang-alpine image (~810 MB, untagged after a build run)
# and give it a stable name. The size and `golang/.../go test` lines distinguish
# it from the small ~18 MB zddc-server runtime image.
podman images --filter dangling=true --format '{{.Size}}\t{{.ID}}' | sort -h | tail
podman tag <id> localhost/zddc-go:1.24

# If you have no <none> 810 MB image (fresh machine), pull directly:
podman pull docker.io/library/golang:1.24-alpine
podman tag docker.io/library/golang:1.24-alpine localhost/zddc-go:1.24
```

 Canonical invocation:

```sh
podman run --rm --network=host \
  -v "$PWD":/src:Z \
  -v /tmp/gocache:/root/go/pkg/mod:Z \
  -w /src/zddc \
  -e GOPROXY=https://proxy.golang.org \
  -e GOSUMDB=off \
  -e GOPRIVATE= \
  localhost/zddc-go:1.24 \
  go test ./...
```

Why each flag:
- `--network=host` — the alpine image's TLS chain can't shake hands with `gopkg.in` directly (sandbox hits "Connection reset by peer"); host networking + the proxy below works around it.
- `GOPROXY=https://proxy.golang.org` — fetch via the public proxy. Without this, the build-image's baked `GOPRIVATE=*` forces direct VCS, which fails on `gopkg.in/natefinch/lumberjack.v2`.
- `GOSUMDB=off` — sum.golang.org isn't reachable from the sandbox either; we already trust the proxy.
- `GOPRIVATE=` (empty) — explicit override of the image's `GOPRIVATE=*`, which is a leftover from how `./build` does in-container compilation and would otherwise re-trigger direct fetch.
- `/tmp/gocache` mount — persistent module cache across runs.

Run-it-once-per-session pattern: alias it. Do **not** `apt install golang` on the host — the image is the source of truth for the version pin, so dev and CI compile against the same Go.

### Run (development)

```sh
ZDDC_ROOT=/path/to/your/archive ZDDC_TLS_CERT=none ZDDC_ADDR=:8080 \
  go run ./cmd/zddc-server
```

For a release binary downloaded from `zddc.varasys.io/releases/`:

```sh
curl -O https://zddc.varasys.io/releases/zddc-server_stable_linux-amd64
chmod +x zddc-server_stable_linux-amd64
ZDDC_ROOT=/path/to/your/archive ZDDC_TLS_CERT=none ZDDC_ADDR=:8080 \
  ./zddc-server_stable_linux-amd64
```

### Key environment variables

| Variable | Default | Purpose |
|---|---|---|
| `ZDDC_ROOT` | *(required)* | Path to served file tree |
| `ZDDC_ADDR` | `:8443` | Bind address |
| `ZDDC_EMAIL_HEADER` | `X-Auth-Request-Email` | Header set by upstream proxy with user email (oauth2-proxy / nginx auth-request convention) |
| `ZDDC_INDEX_PATH` | `.archive` | Virtual archive index URL segment |
| `ZDDC_LOG_LEVEL` | `info` | Logging verbosity |
| `ZDDC_CORS_ORIGIN` | *(empty)* | Comma-separated CORS allowlist; empty (default) disables CORS — appropriate for embedded-tools deployments where tools and data are same-origin. Set explicitly only for self-hosted tools at a different host (e.g. `https://tools.acme.com`) or the CDN-bootstrap pattern (`https://zddc.varasys.io`). |
| `ZDDC_INSECURE` | *(empty)* | Must be `1` to allow startup with no `<ZDDC_ROOT>/.zddc`. Without it, the server refuses to start because no `.zddc` files anywhere → public-by-default. Set only for deliberately-public archives. |
| `ZDDC_NO_AUTH` | *(empty)* | `1` skips ACL enforcement entirely on this instance. On a master: anyone reads everything (dev / trusted-LAN read-only deployments). On a downstream proxy/cache/mirror: trust upstream's filtering, don't re-evaluate ACLs locally. **Distinct from `ZDDC_INSECURE`** (which gates a startup safety check). |
| `ZDDC_UPSTREAM` | *(empty)* | Master URL (`https://master.example.com`). When set, the binary runs as a **client** (downstream proxy/cache/mirror) instead of a master — the master-side machinery (archive index, apps server, watcher, OPA, ACL middleware, token store) is replaced by the cache layer in `zddc/internal/cache/`. `--root` becomes the cache directory. **Setting this also downgrades the `--addr` default to `127.0.0.1:8443` (loopback)** — the cache forwards a bearer to upstream without authenticating the local caller, so non-loopback binds with `ZDDC_BEARER_FILE` set are refused unless `ZDDC_INSECURE_DIRECT=1` is also set. |
| `ZDDC_MODE` | `cache` | Client mode: `proxy` (forward live, no persistence), `cache` (default; persist responses on access), `mirror` (phase 3 — currently behaves like `cache`). Ignored when `ZDDC_UPSTREAM` is empty. |
| `ZDDC_BEARER_FILE` | *(empty)* | Path to a 0600 file containing the master-issued token (see `/.tokens` on the master). Forwarded as `Authorization: Bearer …` to upstream on every request. Ignored when `ZDDC_UPSTREAM` is empty. |
| `ZDDC_SKIP_TLS_VERIFY` | *(empty)* | `1` accepts self-signed / untrusted upstream certs. Distinct from `ZDDC_NO_AUTH`. Dev / internal-CA scenarios only. |
| `ZDDC_MIRROR_SUBTREE` | *(empty)* | Comma-separated URL subtrees the access-triggered mirror walker keeps current (e.g. `/Vendors/Acme,/Public`). Empty + `ZDDC_MODE=mirror` = full mirror (`/`). Ignored when `ZDDC_MODE != mirror`. |
| `ZDDC_MIRROR_MIN_INTERVAL` | `1h` | Minimum gap between walks of the same mirror subtree. Idle subtrees generate zero upstream traffic until next access. Format is Go `time.ParseDuration`. |
| `ZDDC_OPA_URL` | `internal` | Policy decider endpoint. `internal` (default) = in-process Go evaluator (same `.zddc` cascade we always had). `http(s)://...` or `unix:///...` = external OPA — every access decision becomes a `POST /v1/data/zddc/access/allow` to the configured endpoint. Federal customers with their own audited Rego use this; commercial deployments leave it `internal`. |
| `ZDDC_OPA_FAIL_OPEN` | *(empty)* | External OPA only. `1` = allow on transport error; default = fail closed (deny). |
| `ZDDC_OPA_CACHE_TTL` | `1s` | External OPA only. Per-decision cache TTL — amortizes round-trips on bursty patterns (e.g. `.archive` listings hit the same `(email, dir)` tuple many times). `0` disables. Format is Go `time.ParseDuration`. |
| `ZDDC_ACCESS_LOG` | `<ZDDC_ROOT>/.zddc.d/logs/access-<host>.log` | JSON-line audit log (lumberjack-rotated, 100 MB / 10 backups / 90 days, gzipped). Server auto-mkdirs the parent. Set explicitly to empty (`--access-log=`) to disable. Per-host filename + `host` field in every record so multi-replica deployments writing to the same `.zddc.d/` dir disambiguate cleanly. |

### URL handling

**URLs are case-insensitive.** The dispatcher canonicalizes `r.URL.Path` against on-disk casing before any handler runs (`zddc/internal/fs/resolve.go ResolveCanonical`). Per segment: lowercase variant wins if it exists on disk; otherwise exact-case wins; otherwise readdir+CI scan with the lowercase variant winning the tiebreak when multiple case variants are siblings on disk. Walk stops at the first segment that doesn't exist so virtual prefixes (`.archive`, `.profile`, `.tokens`, `.api`, `.auth`) and 404 paths flow through with their tail preserved verbatim.

**File and folder names preserve case on disk.** The canonicalization is purely a URL→filesystem-name mapping; nothing renames anything. Lowercase is the *project-wide canonical* convention, and auto-created folders in `internal/zddc/ensure.go` (the per-party `archive/<party>/{working,staging,reviewing,incoming}/`) and the server's own state dirs (`.zddc.d/tokens/`, `.zddc.d/outbox/`, `.zddc.d/logs/`) are all lowercase by string literal. Operators can drop a `Mixed-Case-Folder/` and it stays mixed-case.

**Audit log captures the as-typed path.** `AccessLogMiddleware` snapshots `r.URL.Path` before dispatch rewrites it; the audit record's `path` field is what the client sent. When canonicalization changed it, a `resolved_path` field is added.

**`.zip` files are navigable directories.** `GET …/Foo.zip/` → JSON listing of the zip's members (or browse HTML); `GET …/Foo.zip/sub/doc.pdf` → that one member, extracted and streamed (Range/ETag via `http.ServeContent`); `GET …/Foo.zip` (no slash) → the raw `.zip` download, unchanged. Write methods to a path inside a `.zip` → 405 (read-only). ACL = the chain of the directory *containing* the zip (a zip has no `.zddc`, like `.archive`). Code: `internal/zipfs` (member listing/extraction with a zip-slip guard) + `handler.ServeZip`, routed by `splitZipPath` in `dispatch` *before* the file-API branch (gated by a cheap `.zip/` substring check so ordinary requests don't pay an `os.Stat`-per-segment walk). Client-side, `shared/zip-source.js` (`ZipDirectoryHandle`/`ZipFileHandle` over JSZip) gives the archive and browse tools the same navigation offline. Archive treats a `.zip` whose name minus `.zip` parses as a transmittal-folder name as that transmittal folder (`isTransmittalFolderZip` in `archive/js/parser.js`); browse expands any `.zip`. Nested zips: the server serves one level (`…/Foo.zip/inner.zip` is the inner zip's bytes; `…/Foo.zip/inner.zip/` isn't a listing) — clients that need deeper nesting fetch the inner zip whole and recurse with JSZip.

**`GET /dir/?zip=1` — subtree download.** Streams an `application/zip` of every readable file under `/dir/` (recursively), `Content-Disposition: attachment; filename="<dir>.zip"`, `X-ZDDC-Source: subtree-zip`. ACL-filtered per file's containing-dir `.zddc` chain (per-dir decision cache, same as `serveArchiveListing`); skips `.`/`_`-prefixed entries (`.zddc`, `_template`, `_app`); adds a `.zip` *file* it meets as opaque bytes (does not recurse). Streamed, so an empty/fully-denied subtree is a valid empty zip, not a 403. The query check is in `dispatch`'s `info.IsDir()` branch right after the directory ACL gate (so it works on `/dir` and `/dir/`); code: `handler.ServeSubtreeZip`. The browse tool's toolbar "Download (zip)" button uses it in server mode; offline it bundles the picked folder with JSZip (`confirm()` above ~2000 files / ~500 MB).

### Client mode (proxy / cache / mirror)

When `--upstream <url>` is set, the binary runs as a **downstream client** of another zddc-server instead of a master. `cmd/zddc-server/main.go` short-circuits to `runClient(cfg)`, which builds a `*cache.Cache` from `zddc/internal/cache/` and uses it as the entire request handler — no archive index, no apps server, no watcher, no OPA decider, no ACL middleware, no token store.

Three modes via `--mode <proxy|cache|mirror>` (default `cache`). Cache directory layout is intentionally a normal ZDDC root: `<master>/foo/bar.txt` → `<root>/foo/bar.txt`. Unset `--upstream` and the same root serves as a plain master, useful for portable offline snapshots.

Pipeline:
- Cache hit → serve immediately + background `If-Modified-Since` revalidate (304 no-op, 200 overwrite, 403/404 purge).
- Cache miss → forward to upstream; stream response simultaneously to client and a tmp-file atomically renamed into the cache.
- Network error + cached version → serve stale + `X-ZDDC-Cache: offline`.
- Network error + no cache → 503 + `X-ZDDC-Cache: offline`.
- Directory listings cached as `<dir>/.zddc-listing.<html|json>` sidecars (Accept-varied).
- `Cache-Control: no-store` / `private` responses pass through but are not persisted.
- **Writes** (PUT / POST / DELETE) forward to upstream when online; on transport error, queue in `<root>/.zddc-outbox/<id>/` (meta + body) and return `202 Accepted` + `X-ZDDC-Cache: queued`. Background loop replays in order — 2xx deletes the entry, 412 → `<id>.conflict-<ts>/`, 4xx-other drops, 5xx defers. PUT/DELETE include `If-Unmodified-Since` from the cached mtime so the master can reject conflicting writes.
- **Mirror mode** (`--mode mirror`): adds an access-triggered subtree walker (rate-limited via `--mirror-min-interval`, default 1h) that recursively pre-fetches under `--mirror-subtree`s; idle mirrors generate zero upstream traffic.

Two-instance smoke test recipe:

```sh
# Master.
mkdir -p /tmp/m && echo 'admins: [you@example.com]' > /tmp/m/.zddc
echo "hello" > /tmp/m/hello.txt
zddc-server --root /tmp/m --addr 127.0.0.1:18443 --tls-cert=none --no-auth &

# Client (cache mode).
mkdir -p /tmp/c
zddc-server --root /tmp/c --addr 127.0.0.1:18444 --tls-cert=none \
  --upstream http://127.0.0.1:18443 --mode cache --no-auth &

curl -sI http://127.0.0.1:18444/hello.txt | grep -i x-zddc-cache  # → miss
curl -sI http://127.0.0.1:18444/hello.txt | grep -i x-zddc-cache  # → hit
ls /tmp/c                                                          # → hello.txt + .zddc-upstream marker
kill %1; sleep 1
curl -sI http://127.0.0.1:18444/hello.txt | grep -i x-zddc-cache  # → hit (still served from disk)
curl -si http://127.0.0.1:18444/never.txt | head -1                # → 503
```

`X-ZDDC-Cache` response header values: `miss`, `hit`, `proxy` (no-persist or directory), `offline` (network unreachable). Useful for browser-side freshness UI.

Implementation: `zddc/internal/cache/cache.go` (a single file). Tests in `zddc/internal/cache/cache_test.go` use `httptest.NewServer` as a fake upstream and cover hit/miss/offline/range/bearer-forwarding/no-store paths.

### Bearer tokens (CLI auth)

zddc-server self-issues bearer tokens for CLI / non-browser callers. No external IDP, no JWKS rotation. Source of truth: `<ZDDC_ROOT>/.zddc.d/tokens/<sha256-hex>` — a YAML file per token with `email`, `created`, `expires`, `description`. Filename is the **hash** of the token; the plaintext is never persisted.

User flow: sign in to the master in a browser, visit `/.tokens`, click "Create token," copy the value (shown once). Store in a 0600 file and pass `--bearer-file <path>` to a CLI that calls back into zddc-server, or send `Authorization: Bearer <token>` directly from scripts.

Endpoints:
- `GET /.tokens` — HTML self-service page (gated by browser auth).
- `GET/POST /.api/tokens` — list / create. Plaintext returned **only** on POST response.
- `DELETE /.api/tokens/<id>` — revoke. `<id>` is the 8-char short ID or full hash.

Validation flow inside the request path: `ACLMiddleware` checks for `Authorization: Bearer …` first; on success, sets the request email from the token file. On any failure (unknown / expired / store unavailable), returns 401 — there is no fallback to header-based auth, so a misconfigured client can't silently masquerade as anonymous. If no Bearer is present, the existing `cfg.EmailHeader` path runs unchanged.

The tokens directory inherits the existing `.zddc.d/` exclusion: dot-prefix segments 404 from direct GETs, and `fs.ListDirectory` filters them from listings. **Verify on any new deployment by attempting `GET /.zddc.d/tokens/anything` and confirming 404.**

Implementation: `zddc/internal/auth/` (storage), `zddc/internal/handler/tokenhandler.go` (HTTP layer), middleware extension in `zddc/internal/handler/middleware.go`.

### Admin elevation (sudo-style)

Admins are treated as normal users by default; admin escape hatches (WORM bypass, auto-own takeover, `.zddc` edit authority, profile admin scaffolds) require an explicit per-request opt-in. The toggle lives in every tool's header (left of the theme button) and writes a `zddc-elevate=1` cookie (Max-Age=1800, SameSite=Lax) — 30-minute sudo window before it auto-expires.

Server-side the model is `zddc.Principal{Email, Elevated}`. `ACLMiddleware` builds it once per request and stashes it in context; `IsAdmin` / `IsSubtreeAdmin` / `CanEditZddc` take a `Principal` parameter rather than a bare email. That signature change is the enforcement mechanism — the compiler tells you when an admin call site doesn't thread elevation, so a "forgot to gate this" mistake doesn't compile. `PrincipalFromContext(r)` is the one-call-per-site bundling helper.

Bearer tokens are **implicitly elevated** — CLI clients and the mirror process can't toggle a cookie, and their authority is the bearer's full grant by design. Browser sessions elevate only when the user opts in.

`/.profile/access` exposes `can_elevate` (elevation-independent "does this email have any admin grant anywhere?") so the header toggle can render itself for an un-elevated admin who hasn't opted in yet. The access log captures `elevated=<true|false>` per request for forensics.

Implementation: `zddc/internal/zddc/admin.go` (Principal struct + gated functions), `zddc/internal/handler/middleware.go` (cookie/bearer → ElevatedKey context value), `shared/elevation.{js,css}` (header toggle UI, concat'd into every tool's bundle).

### Release tagging

zddc-server has no separate release script. The top-level `./build release [version]` is the canonical path: it cross-compiles the binaries inside the containerized Go toolchain, copies them into `dist/release-output/` with their per-platform canonical symlinks (`zddc-server_<platform>` → `zddc-server_v<X.Y.Z>_<platform>`), regenerates the per-version + canonical stub pages, refreshes the index, and tags `zddc-server-v<X.Y.Z>` alongside the seven HTML-tool tags.

```sh
./build release            # lockstep stable, coordinated next version
./build release 1.2.0      # lockstep stable, explicit version
./build beta               # internal SHA snapshot for the BMC dev chart
./deploy --releases        # publish the bundle to /srv/zddc/releases/
```

The script tags every tool but does NOT push — finish with `git push origin main && git push origin --tags` (and run `./deploy` to put the artifacts on the live site).

**Versioning** — clean semver. Stable cuts emit one `<tool>-vX.Y.Z` tag per tool, all 8 sharing the same X.Y.Z. No `-alpha.N` / `-beta.N` counter tags — the canonical URL `<tool>.html` is the stable URL; counters would defeat that. Historical per-tool independent tags (`archive-v0.0.2`, `zddc-server-v0.0.7`, etc.) stay as artifacts; the next coordinated cut jumps every tool to the same number.

**Binary distribution** — `/srv/zddc/releases/zddc-server_<X>_<platform>` (on the deploy host) are real static files served from `zddc.varasys.io/releases/`. No Codeberg release assets, no `$CODEBERG_TOKEN`, no third-party mirror, no LFS. The matrix-cell link points at `zddc-server_<X>.html`, a generated stub page that surfaces the four platform downloads in one click.

There is no CI for this — solo workflow benefits from one canonical
local path that fails loudly and visibly on the developer's terminal.

### Notes

- No external test framework yet — Go unit tests run with `go test ./...` inside `zddc/`. The Go toolchain is not on the host; use the `localhost/zddc-go:1.24` image as documented in the **Test** subsection above.
- Portfolio files (`*.portfolio`) in the served tree appear as virtual group directories
- Every folder under a project exposes a `.archive` virtual directory backed by that **project's** index bucket — the project is the first slash-separated segment of the contextPath. Depth within a project doesn't change scope: `/ProjectA/sub/sub/.archive/X.html` resolves the same as `/ProjectA/.archive/X.html`, just with a different URL prefix on the listing entries. The flat listing emits two entries per tracking number: `<tracking>.html` (highest base rev) and `<tracking>_<rev>.html` (each specific base rev). Both **serve in place** — the handler streams the first chronologically received copy's bytes back at the `.archive/` URL without redirecting. The per-transmittal URL is intentionally hidden so external links of the form `.archive/<tracking>.html#section` keep tracking the latest revision (a redirect would expose the snapshot URL and people would forward THAT instead). Cache-Control is `no-cache` so each load revalidates against the on-disk file's Last-Modified/ETag; when a new revision lands the resolver picks it and the browser refetches. Modifier files (`<tracking>_<rev>+C1.html` etc.) remain reachable via the resolver but are not surfaced in the listing — they're return traffic, not primary documents. `/.archive/` at the very root has no project segment and returns 404 — stable references must include the project directory. Within one project, two different files claiming the same `(tracking, rev)` are an authoring mistake; chronological winner still wins, but a `WARN` is emitted with both paths. ACL is enforced twice: the listing endpoint is gated by the contextPath's `.zddc` chain, and each entry is then filtered against the ACL of its resolved file's directory — per-target denials return 404 rather than 403 to avoid leaking that the tracking number exists in another subtree.
- ACL is enforced via cascading `.zddc` YAML files — first-explicit-match-wins evaluated bottom-up (deepest level first), with deny checked before allow within a single `.zddc`; default-deny when any `.zddc` exists in the chain. Authentication is delegated to the upstream proxy via the `X-Auth-Request-Email` header (configurable with `ZDDC_EMAIL_HEADER`). Operator-facing detail, anti-patterns, worked layouts, the verify-it-works recipe, and the federal-readiness gap analysis are in `zddc/README.md` § "Access control: the `.zddc` cascade." The architectural framing (cooperating layers, commercial-vs-federal trust model, why archive auto-serves at every directory) is in `ARCHITECTURE.md` § "Server security model."
- `.zddc` schema also supports a top-level `admins:` glob list, peer to `acl.allow`/`acl.deny`. Honored **only** at the root `.zddc` (subdir `admins` entries are ignored to prevent privilege escalation via subtree write access). Drives the built-in debug dashboard at `/.admin/` (sub-routes: `/whoami`, `/config`, `/logs`); non-admin requests get 404 so the page is invisible. See `zddc/README.md` § "Admin Debug Page".
- `GET /.auth/admin` is a **forward_auth target** for upstream proxies — returns 200 if the request's `X-Auth-Request-Email` is in the root `.zddc` `admins:` list, 403 otherwise. No body, no UI. Used by an upstream proxy to gate an admin-only sub-app on root-admin status without that app learning about auth. zddc-server's own routes use the regular `.zddc` cascade ACL — they do NOT go through this endpoint.
- **Reserved entry prefixes** under `ZDDC_ROOT`: `.`-prefixed entries are excluded from listings AND 404 on direct fetch (only `.archive` and `.admin` are exempt) — for invisible side-state like dev-shell home dirs. `_`-prefixed entries are excluded from listings only — for operator scaffolding like the `_template/` directory created by the self-contained install snippet, still reachable by direct URL. Drop side-state under `_` if it should be linkable; under `.` if it should be unreachable.
- **Caching on embedded tool HTMLs** (landing, browse served at `/`, plus the five canonical app HTMLs at `<dir>/<app>.html`): `Cache-Control: public, max-age=0, must-revalidate` + content-addressed `ETag` (sha256 hex prefix). Browser revalidates on every load; matching ETag returns `304 Not Modified` with empty body. ETag changes only when the binary is redeployed (computed once at startup from `EmbeddedBytes` + `BuildVer`, memoized).
- **Compression**: gzip middleware (`github.com/klauspost/compress/gzhttp`) wraps the entire mux. Skipped for bodies under 1 KB and for 304 responses. Roughly 75% size reduction on tool HTMLs and JSON listings.
- **Public landing page**: `GET /` (HTML or JSON) bypasses the directory-level ACL gate so anonymous callers see the project picker. Per-project filtering inside `fs.ListDirectory` still hides projects the caller can't reach. Subdirectory ACL gates remain in force.
- **Audit log**: every request is mirrored to a JSON-line file under `<ZDDC_ROOT>/.zddc.d/logs/access-<host>.log` (configurable via `--access-log` / `ZDDC_ACCESS_LOG`, opt out with empty). Lumberjack rotation (100 MB / 10 backups / 90 days, gzip). Hostname is in both the filename and every record's `host` field — multi-replica deployments sharing one `.zddc.d/` dir disambiguate cleanly.
- **HTTP timeouts**: `ReadHeaderTimeout: 10s, ReadTimeout: 60s, WriteTimeout: 60s, IdleTimeout: 120s`. Slowloris-resistant; legit traffic completes in milliseconds even with gzip.
