feat(zddc-server): reviewing/ virtual aggregator + mdedit at the URL

Implements the reviewing/ aggregator described in the saved
project memory (~/.claude/projects/-home-user-src-zddc/memory/
project_reviewing_folder_design.md). reviewing/ stays in
VirtualOnlyCanonicalNames — never materialised on disk — and is
served as a join over archive/<party>/received/, archive/<party>/
issued/, and staging/, recomputed on every read.

Two depths, both trailing-slash:

  GET <project>/reviewing/?json=1
    → array of virtual <tracking>/ entries, one per submittal in
      archive/<party>/received/ that doesn't yet have a matching
      archive/<party>/issued/ entry. Sorted by tracking. URLs stay
      under reviewing/ so the user can drill into the per-submittal
      view. ACL: per-party, filtered like fs.ListDirectory.

  GET <project>/reviewing/<tracking>/?json=1
    → array of two virtual entries, received/ + staged/, with
      canonical URLs pointing back to archive/<party>/received/...
      and staging/... respectively. staged/ is omitted when no
      response draft exists yet.

When the response moves staging/ → archive/<party>/issued/, the
entry vanishes from depth-0 on the next listing. No mutation of
the reviewing/ subtree itself; pure join, recomputed on read.

Front-end at <project>/reviewing[/<tracking>/] is mdedit (per
user request). DefaultAppAt + AppAvailableAt extended to recognise
"reviewing" as a canonical mdedit-bearing folder. The polyfill in
shared/zddc-source.js is updated to follow listing entries' explicit
url field when present (absolute or root-relative) — that's how
mdedit's tree follows the depth-1 received/ + staged/ links into
the canonical archive/staging subtrees.

Dispatcher routing in zddc-server/main.go:
  - GET <project>/reviewing/[<tracking>/] with Accept: json
    → ServeReviewing
  - GET <project>/reviewing/[<tracking>/] with Accept: html
    → mdedit (rooted at the virtual path; polyfill fetches the
      JSON listing on its own)
  - GET <project>/reviewing (no slash) → mdedit (via DefaultAppAt)
  - GET <project>/reviewing/<tracking> (no slash) → 301 to slash form

Tests:
  - handler/reviewinghandler_test.go (6 cases): IsReviewingPath
    classification + ServeReviewing depth-0/depth-1 with and without
    staged drafts + 404 on unknown tracking + empty when archive/ is
    absent.
  - apps/availability_test.go updated: reviewing/ now expects mdedit
    rather than "" (no default).
  - cmd/zddc-server/main_test.go: TestDispatchEmptyCanonicalProjectFolders
    extended to assert reviewing → mdedit at the no-slash form;
    older "no-slash/reviewing → 301" test removed.

Future work (not in this commit): write translation. Editing a file
under reviewing/<tracking>/staged/<f>.md works today because the
polyfill rewrites to /<project>/staging/<response>/<f>.md before
fetching — the user's URL bar moves to the canonical path on click.
A virtual-filesystem mode where the URL bar stays under reviewing/
throughout would require server-side write rewriting (translate
PUT/DELETE on reviewing/.../staged/... into the canonical staging/
path). Not needed for the MVP — links in mdedit's tree work.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

shared/zddc-source.js

@@ -171,7 +171,24 @@
             for (var i = 0; i < entries.length; i++) {
                 var e = entries[i];
                 var rawName = stripSlash(e.name);
-                var childUrl = joinUrl(url, rawName, e.is_dir);
+                // Listing entries can carry an explicit URL for virtual
+                // links (e.g. the reviewing-aggregator's received/+staged/
+                // entries point to canonical archive/+staging paths).
+                // Use it when present so navigation follows the listing's
+                // own routing rather than computing a synthetic child URL
+                // off the parent. Caddy-shape listings don't set url
+                // (or set it to a relative form) — joinUrl handles those.
+                var childUrl;
+                if (e.url && /^https?:\/\/|^\//.test(e.url)) {
+                    // Absolute or root-relative: use as-is, normalised against origin.
+                    var u = e.url;
+                    if (u[0] === '/') {
+                        u = location.origin + u;
+                    }
+                    childUrl = u;
+                } else {
+                    childUrl = joinUrl(url, rawName, e.is_dir);
+                }
                 if (e.is_dir) {
                     yield new HttpDirectoryHandle(childUrl, rawName);
                 } else {

zddc/cmd/zddc-server/main.go

@@ -841,6 +841,41 @@ func dispatch(cfg config.Config, idx *archive.Index, ring *handler.LogRing, apps
 					}
 				}
 			}
+			// Reviewing aggregator. <project>/reviewing/[<tracking>/] is
+			// a virtual view. With trailing slash:
+			//   - JSON request → aggregator listing (handler.ServeReviewing)
+			//   - HTML request → mdedit, rooted at the reviewing/ path.
+			//                    mdedit's polyfill then fetches the JSON
+			//                    listing on its own.
+			// Without trailing slash, depth-3 (reviewing/<tracking>) 301s
+			// to the slash form; depth-2 (reviewing) falls through to the
+			// canonical-folder block below where DefaultAppAt routes to
+			// mdedit and the no-slash branch serves it directly.
+			if r.Method == http.MethodGet || r.Method == http.MethodHead {
+				if proj, tracking, ok := handler.IsReviewingPath(urlPath); ok {
+					if !strings.HasSuffix(urlPath, "/") {
+						if tracking != "" {
+							http.Redirect(w, r, urlPath+"/", http.StatusMovedPermanently)
+							return
+						}
+						// Depth-2 no-slash falls through to canonical-folder block.
+					} else {
+						chain, _ := zddc.EffectivePolicy(cfg.Root, filepath.Join(cfg.Root, proj))
+						if allowed, _ := policy.AllowFromChain(r.Context(), handler.DeciderFromContext(r), chain, email, urlPath); !allowed {
+							http.Error(w, "Forbidden", http.StatusForbidden)
+							return
+						}
+						if strings.Contains(r.Header.Get("Accept"), "application/json") {
+							handler.ServeReviewing(cfg, w, r, proj, tracking)
+							return
+						}
+						if appsSrv != nil {
+							appsSrv.Serve(w, r, "mdedit", chain, absPath)
+							return
+						}
+					}
+				}
+			}
 			// Canonical project-root folder fallback. <project>/{archive,
 			// working,staging,reviewing}[/] should land on a usable view
 			// (default tool or empty listing) rather than 404, so the

zddc/cmd/zddc-server/main_test.go

@@ -529,6 +529,10 @@ func TestDispatchEmptyCanonicalProjectFolders(t *testing.T) {
 		{"working", "ZDDC Markdown"},
 		{"staging", "ZDDC Transmittal"},
 		{"archive", "ZDDC Archive"},
+		// reviewing/ also routes to mdedit; the polyfill follows the
+		// virtual aggregator's listing into canonical archive/+staging
+		// paths from there.
+		{"reviewing", "ZDDC Markdown"},
 	}
 	for _, tc := range noSlashDefaultApp {
 		t.Run("no-slash/"+tc.stage+" → default app", func(t *testing.T) {
@@ -544,20 +548,6 @@ func TestDispatchEmptyCanonicalProjectFolders(t *testing.T) {
 		})
 	}
 
-	// reviewing/ has no default tool — no-slash form should 301 to
-	// the slash form (which then renders the empty listing).
-	t.Run("no-slash/reviewing → 301 to slash", func(t *testing.T) {
-		req := httptest.NewRequest(http.MethodGet, "/Project/reviewing", nil)
-		rec := httptest.NewRecorder()
-		dispatch(cfg, idx, ring, appsSrv, nil, rec, req)
-		if rec.Code != http.StatusMovedPermanently {
-			t.Errorf("status=%d, want 301", rec.Code)
-		}
-		if loc := rec.Header().Get("Location"); loc != "/Project/reviewing/" {
-			t.Errorf("Location=%q, want %q", loc, "/Project/reviewing/")
-		}
-	})
-
 	// Non-canonical missing folder still 404s (the fallback is
 	// scoped to the four canonical names, not a blanket "missing →
 	// empty" rule).

zddc/internal/apps/availability.go

@@ -14,9 +14,11 @@ import (
 //   - classifier: requestDir is, or descends from, a folder named
 //     "working", "staging", or "incoming" (the directories where
 //     in-flight files get classified)
-//   - mdedit: requestDir is, or descends from, a "working" folder
+//   - mdedit: requestDir is, or descends from, a "working" or
-//     (where markdown drafts are written and edited, including review
+//     "reviewing" folder. working/ is the drafting workspace;
-//     responses drafted in working/<rs-name>/)
+//     reviewing/ is the virtual aggregation view of pending review
+//     responses (server-rendered listings; mdedit follows the
+//     listing's canonical URLs via the polyfill).
 //   - transmittal: requestDir is, or descends from, a "staging" folder
 //     (where outgoing transmittals are prepared)
 //   - landing: only at the deployment root (the project picker)
@@ -41,7 +43,7 @@ func AppAvailableAt(root, requestDir, app string) bool {
 	case "classifier":
 		return inAncestorWithName(root, requestDir, "working", "staging", "incoming")
 	case "mdedit":
-		return inAncestorWithName(root, requestDir, "working")
+		return inAncestorWithName(root, requestDir, "working", "reviewing")
 	case "transmittal":
 		return inAncestorWithName(root, requestDir, "staging")
 	}
@@ -81,6 +83,8 @@ func inAncestorWithName(root, requestDir string, names ...string) bool {
 //   - <project>/archive/<party>/...        → "archive"
 //   - <project>/staging/...                → "transmittal"
 //   - <project>/working/...                → "mdedit"
+//   - <project>/reviewing/...              → "mdedit" (operates on the
+//                                              virtual aggregator listing)
 //   - any other directory                  → "" (no default)
 //
 // The mdl rule wins over the broader archive rule because the table
@@ -120,6 +124,8 @@ func DefaultAppAt(root, requestDir string) string {
 		return "transmittal"
 	case "working":
 		return "mdedit"
+	case "reviewing":
+		return "mdedit"
 	}
 	return ""
 }

zddc/internal/apps/availability_test.go

@@ -96,8 +96,11 @@ func TestDefaultAppAt(t *testing.T) {
 		// mdl wins over the broader archive rule.
 		{root + "/Project-A/archive/Acme/mdl", "tables"},
 		{root + "/Project-A/archive/Acme/mdl/anything-deeper", "tables"},
-		// reviewing/ is virtual — no default tool wired here yet.
+		// reviewing/ is virtual but mdedit is wired as the default
-		{root + "/Project-A/reviewing", ""},
+		// tool; the polyfill follows the listing's canonical URLs
+		// into archive/ and staging/ for the actual files.
+		{root + "/Project-A/reviewing", "mdedit"},
+		{root + "/Project-A/reviewing/123-EM-SUB-0001", "mdedit"},
 		// Random non-canonical folder names → no default.
 		{root + "/Project-A/scratch", ""},
 		// Case-fold on canonical names.

zddc/internal/handler/reviewinghandler.go

@@ -0,0 +1,264 @@
+package handler
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/config"
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/listing"
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/policy"
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/zddc"
+)
+
+// IsReviewingPath classifies a URL as a reviewing-aggregator path and
+// extracts (project, tracking). The aggregator is a virtual view at:
+//
+//	<project>/reviewing/                 → depth 0: list pending submittals
+//	<project>/reviewing/<tracking>/      → depth 1: list received/ + staged/
+//
+// Anything deeper than depth 1 returns ok=false; the depth-1 listing
+// emits canonical URLs (under archive/ and staging/) so navigation past
+// that point goes through the regular file-tree handlers, not back into
+// the virtual reviewing/ subtree.
+//
+// Trailing slash on either depth is required and tolerated. Match on
+// "reviewing" is case-insensitive.
+func IsReviewingPath(urlPath string) (project, tracking string, ok bool) {
+	parts := strings.Split(strings.Trim(urlPath, "/"), "/")
+	if len(parts) < 2 || !strings.EqualFold(parts[1], "reviewing") {
+		return "", "", false
+	}
+	switch len(parts) {
+	case 2:
+		return parts[0], "", true
+	case 3:
+		return parts[0], parts[2], true
+	default:
+		return "", "", false
+	}
+}
+
+// pendingSubmittal is one row of the aggregator's view: a submittal in
+// archive/<party>/received/ that doesn't yet have a matching entry in
+// archive/<party>/issued/, optionally paired with an in-progress
+// response folder under staging/.
+type pendingSubmittal struct {
+	tracking     string    // canonical tracking number, e.g. "123456-ST-SUB-0026"
+	party        string    // party folder name, e.g. "Acme"
+	receivedURL  string    // /<project>/archive/<party>/received/<folder>/
+	stagedURL    string    // /<project>/staging/<folder>/  or "" if no draft yet
+	lastModified time.Time // newer of the two folders' mtimes
+}
+
+// computePending walks the project's archive/ and staging/ subtrees to
+// build the virtual reviewing-aggregator view.
+//
+// Algorithm:
+//
+//  1. Index staging/<folder>/ by tracking number.
+//  2. For each party under archive/<party>/:
+//     a. Index archive/<party>/issued/ by tracking number.
+//     b. For each archive/<party>/received/<folder>:
+//     - skip folders that don't parse as transmittal folders.
+//     - skip if tracking already in issued (response complete).
+//     - emit a pendingSubmittal pointing at the canonical received
+//     URL and (if found) the matching staging URL.
+//
+// ACL: per-party. The caller's email + decider are consulted on the
+// archive/<party>/received/ subtree before reading its contents — a
+// party the caller can't see at upstream is omitted entirely (no info
+// leak via tracking-number listing).
+//
+// Missing intermediate folders (archive/, party/issued/, staging/) are
+// not errors; they just produce empty intermediate sets. This matches
+// the lazy-instantiation pattern of the canonical project folders.
+func computePending(ctx context.Context, decider policy.Decider,
+	fsRoot, project, email string) ([]pendingSubmittal, error) {
+
+	projectAbs := filepath.Join(fsRoot, project)
+	archiveAbs := filepath.Join(projectAbs, "archive")
+	stagingAbs := filepath.Join(projectAbs, "staging")
+
+	// Index staging by tracking → folder name.
+	stagedByTracking := map[string]string{}
+	if entries, err := os.ReadDir(stagingAbs); err == nil {
+		for _, e := range entries {
+			if !e.IsDir() || strings.HasPrefix(e.Name(), ".") {
+				continue
+			}
+			if _, tracking, _, _, ok := zddc.ParseTransmittalFolder(e.Name()); ok {
+				stagedByTracking[tracking] = e.Name()
+			}
+		}
+	}
+
+	parties, err := os.ReadDir(archiveAbs)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	var result []pendingSubmittal
+	for _, p := range parties {
+		if !p.IsDir() || strings.HasPrefix(p.Name(), ".") {
+			continue
+		}
+		party := p.Name()
+		partyAbs := filepath.Join(archiveAbs, party)
+		receivedAbs := filepath.Join(partyAbs, "received")
+
+		// ACL: skip parties whose received/ subtree the caller can't read.
+		// Filtering at the party level is cheaper than per-entry and matches
+		// fs.ListDirectory's omit-denied-subdirs convention.
+		chain, err := zddc.EffectivePolicy(fsRoot, receivedAbs)
+		if err != nil {
+			continue
+		}
+		receivedURLPrefix := "/" + project + "/archive/" + party + "/received/"
+		if allowed, _ := policy.AllowFromChain(ctx, decider, chain, email, receivedURLPrefix); !allowed {
+			continue
+		}
+
+		// Index this party's issued/ trackings (no ACL filter — issued/
+		// is WORM-readable to anyone with party access by design, and
+		// we just need the set membership for matching).
+		issuedTrackings := map[string]bool{}
+		if entries, err := os.ReadDir(filepath.Join(partyAbs, "issued")); err == nil {
+			for _, e := range entries {
+				if !e.IsDir() {
+					continue
+				}
+				if _, tracking, _, _, ok := zddc.ParseTransmittalFolder(e.Name()); ok {
+					issuedTrackings[tracking] = true
+				}
+			}
+		}
+
+		receivedEntries, err := os.ReadDir(receivedAbs)
+		if err != nil {
+			continue
+		}
+		for _, e := range receivedEntries {
+			if !e.IsDir() || strings.HasPrefix(e.Name(), ".") {
+				continue
+			}
+			_, tracking, _, _, ok := zddc.ParseTransmittalFolder(e.Name())
+			if !ok {
+				continue
+			}
+			if issuedTrackings[tracking] {
+				continue // response complete; not pending
+			}
+
+			info, err := e.Info()
+			if err != nil {
+				continue
+			}
+			modTime := info.ModTime()
+
+			sub := pendingSubmittal{
+				tracking:     tracking,
+				party:        party,
+				receivedURL:  receivedURLPrefix + url.PathEscape(e.Name()) + "/",
+				lastModified: modTime,
+			}
+			if stagedFolder, hasDraft := stagedByTracking[tracking]; hasDraft {
+				sub.stagedURL = "/" + project + "/staging/" + url.PathEscape(stagedFolder) + "/"
+				if stagedInfo, err := os.Stat(filepath.Join(stagingAbs, stagedFolder)); err == nil {
+					if stagedInfo.ModTime().After(modTime) {
+						sub.lastModified = stagedInfo.ModTime()
+					}
+				}
+			}
+			result = append(result, sub)
+		}
+	}
+
+	sort.Slice(result, func(i, j int) bool {
+		return result[i].tracking < result[j].tracking
+	})
+	return result, nil
+}
+
+// ServeReviewing emits the aggregator JSON listing for either depth 0
+// (project's full pending list) or depth 1 (one submittal's
+// received/ + staged/ pair). The HTML branch is handled separately by
+// the apps subsystem (mdedit served at the URL); only requests that
+// accept JSON reach here.
+func ServeReviewing(cfg config.Config, w http.ResponseWriter, r *http.Request,
+	project, tracking string) {
+
+	pending, err := computePending(r.Context(), DeciderFromContext(r),
+		cfg.Root, project, EmailFromContext(r))
+	if err != nil {
+		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		return
+	}
+
+	var entries []listing.FileInfo
+	switch tracking {
+	case "":
+		// Depth 0: list pending submittals as virtual <tracking>/ folders.
+		// The URLs stay under reviewing/ so the user can drill into a
+		// per-submittal view.
+		urlPrefix := "/" + project + "/reviewing/"
+		for _, s := range pending {
+			entries = append(entries, listing.FileInfo{
+				Name:    s.tracking + "/",
+				URL:     urlPrefix + url.PathEscape(s.tracking) + "/",
+				ModTime: s.lastModified,
+				IsDir:   true,
+				Virtual: true,
+			})
+		}
+	default:
+		// Depth 1: find the matching pending entry; emit received/ +
+		// staged/ pointing at canonical archive/staging URLs. Clients
+		// using the polyfill follow these URLs out of the virtual
+		// subtree into the real file paths underneath.
+		var match *pendingSubmittal
+		for i := range pending {
+			if pending[i].tracking == tracking {
+				match = &pending[i]
+				break
+			}
+		}
+		if match == nil {
+			http.Error(w, "Not Found", http.StatusNotFound)
+			return
+		}
+		entries = append(entries, listing.FileInfo{
+			Name:    "received/",
+			URL:     match.receivedURL,
+			ModTime: match.lastModified,
+			IsDir:   true,
+			Virtual: true,
+		})
+		if match.stagedURL != "" {
+			entries = append(entries, listing.FileInfo{
+				Name:    "staged/",
+				URL:     match.stagedURL,
+				ModTime: match.lastModified,
+				IsDir:   true,
+				Virtual: true,
+			})
+		}
+	}
+
+	if entries == nil {
+		entries = []listing.FileInfo{}
+	}
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store") // virtual; recompute every time
+	w.Header().Set("X-ZDDC-Source", "reviewing-aggregator")
+	_ = json.NewEncoder(w).Encode(entries)
+}

zddc/internal/handler/reviewinghandler_test.go

@@ -0,0 +1,212 @@
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"testing"
+
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/config"
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/listing"
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/zddc"
+)
+
+func TestIsReviewingPath(t *testing.T) {
+	cases := []struct {
+		path         string
+		wantOK       bool
+		wantProj     string
+		wantTracking string
+	}{
+		{"/Project/reviewing/", true, "Project", ""},
+		{"/Project/reviewing/123-EM-SUB-0001/", true, "Project", "123-EM-SUB-0001"},
+		// Case-insensitive on the literal "reviewing" segment.
+		{"/Project/Reviewing/", true, "Project", ""},
+		{"/Project/REVIEWING/x/", true, "Project", "x"},
+		// No trailing slash: still classified (caller decides redirect).
+		{"/Project/reviewing", true, "Project", ""},
+		{"/Project/reviewing/123/", true, "Project", "123"},
+		// Non-canonical / wrong shape.
+		{"/Project/", false, "", ""},
+		{"/", false, "", ""},
+		{"/Project/working/", false, "", ""},
+		{"/Project/reviewing/x/y/", false, "", ""}, // depth >3 not supported
+	}
+	for _, tc := range cases {
+		gotProj, gotTracking, gotOK := IsReviewingPath(tc.path)
+		if gotOK != tc.wantOK || gotProj != tc.wantProj || gotTracking != tc.wantTracking {
+			t.Errorf("IsReviewingPath(%q) = (%q,%q,%v), want (%q,%q,%v)",
+				tc.path, gotProj, gotTracking, gotOK, tc.wantProj, tc.wantTracking, tc.wantOK)
+		}
+	}
+}
+
+// Test setup: build a synthetic project tree with two parties, one
+// pending submittal each. Verify the aggregator returns:
+//   - depth 0: 2 virtual <tracking>/ entries, sorted, both with
+//     URLs under /<project>/reviewing/
+//   - depth 1: received/ + staged/ entries with canonical URLs
+func TestServeReviewing(t *testing.T) {
+	root := t.TempDir()
+	mustWrite(t, filepath.Join(root, ".zddc"),
+		"acl:\n  permissions:\n    \"*\": rwcda\n")
+
+	// Two parties under archive/, each with a pending submittal.
+	// Acme: submitted but no response staged or issued yet.
+	// Beta: submitted, response staged but not yet issued.
+	pAcmeReceived := filepath.Join(root, "Project", "archive", "Acme", "received",
+		"2025-10-31_001-AB-SUB-0001 (IFR) - Pending acme review")
+	pBetaReceived := filepath.Join(root, "Project", "archive", "Beta", "received",
+		"2025-11-01_002-AB-SUB-0007 (IFR) - Pending beta review")
+	pBetaStaged := filepath.Join(root, "Project", "staging",
+		"2025-11-15_002-AB-SUB-0007 (RSC) - Beta response draft")
+	for _, p := range []string{pAcmeReceived, pBetaReceived, pBetaStaged} {
+		mustMkdir(t, p)
+	}
+	// And a third party (Gamma) where the submittal has BEEN issued —
+	// should NOT appear in the pending list.
+	pGammaReceived := filepath.Join(root, "Project", "archive", "Gamma", "received",
+		"2025-09-01_003-CD-SUB-0099 (IFR) - Already responded")
+	pGammaIssued := filepath.Join(root, "Project", "archive", "Gamma", "issued",
+		"2025-09-15_003-CD-SUB-0099 (RSC) - The response we sent")
+	mustMkdir(t, pGammaReceived)
+	mustMkdir(t, pGammaIssued)
+
+	zddc.InvalidateCache(root)
+
+	cfg := config.Config{
+		Root:        root,
+		EmailHeader: "X-Auth-Request-Email",
+	}
+
+	t.Run("depth-0 lists pending submittals only", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/Project/reviewing/", nil)
+		req.Header.Set("Accept", "application/json")
+		req = req.WithContext(WithEmail(req.Context(), "alice@example.com"))
+		rec := httptest.NewRecorder()
+		ServeReviewing(cfg, rec, req, "Project", "")
+
+		if rec.Code != http.StatusOK {
+			t.Fatalf("status=%d, body=%s", rec.Code, rec.Body.String())
+		}
+		var got []listing.FileInfo
+		if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+			t.Fatalf("decode: %v; body=%s", err, rec.Body.String())
+		}
+		if len(got) != 2 {
+			t.Fatalf("got %d entries, want 2 (Acme + Beta pending; Gamma issued); body=%s",
+				len(got), rec.Body.String())
+		}
+		// Sorted by tracking number → 001-* before 002-*.
+		if got[0].Name != "001-AB-SUB-0001/" {
+			t.Errorf("entries[0].Name=%q, want %q", got[0].Name, "001-AB-SUB-0001/")
+		}
+		if got[1].Name != "002-AB-SUB-0007/" {
+			t.Errorf("entries[1].Name=%q, want %q", got[1].Name, "002-AB-SUB-0007/")
+		}
+		for i, e := range got {
+			if !e.IsDir || !e.Virtual {
+				t.Errorf("entries[%d] IsDir=%v Virtual=%v, want both true", i, e.IsDir, e.Virtual)
+			}
+			// Per-submittal URL stays under reviewing/ (the user can
+			// drill into the per-submittal received/+staged/ view).
+			if e.URL != "/Project/reviewing/"+got[i].Name[:len(got[i].Name)-1]+"/" {
+				t.Errorf("entries[%d].URL=%q, want under /Project/reviewing/", i, e.URL)
+			}
+		}
+	})
+
+	t.Run("depth-1 with staged draft → received/ + staged/", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/Project/reviewing/002-AB-SUB-0007/", nil)
+		req.Header.Set("Accept", "application/json")
+		req = req.WithContext(WithEmail(req.Context(), "alice@example.com"))
+		rec := httptest.NewRecorder()
+		ServeReviewing(cfg, rec, req, "Project", "002-AB-SUB-0007")
+
+		if rec.Code != http.StatusOK {
+			t.Fatalf("status=%d, body=%s", rec.Code, rec.Body.String())
+		}
+		var got []listing.FileInfo
+		if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+			t.Fatalf("decode: %v", err)
+		}
+		if len(got) != 2 {
+			t.Fatalf("got %d entries, want 2 (received/ + staged/); body=%s",
+				len(got), rec.Body.String())
+		}
+		if got[0].Name != "received/" {
+			t.Errorf("entries[0].Name=%q, want %q", got[0].Name, "received/")
+		}
+		// Canonical URL — outside reviewing/ subtree.
+		if want := "/Project/archive/Beta/received/"; !startsWith(got[0].URL, want) {
+			t.Errorf("received URL=%q, want prefix %q", got[0].URL, want)
+		}
+		if got[1].Name != "staged/" {
+			t.Errorf("entries[1].Name=%q, want %q", got[1].Name, "staged/")
+		}
+		if want := "/Project/staging/"; !startsWith(got[1].URL, want) {
+			t.Errorf("staged URL=%q, want prefix %q", got[1].URL, want)
+		}
+	})
+
+	t.Run("depth-1 with no staged draft → received/ only", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/Project/reviewing/001-AB-SUB-0001/", nil)
+		req.Header.Set("Accept", "application/json")
+		req = req.WithContext(WithEmail(req.Context(), "alice@example.com"))
+		rec := httptest.NewRecorder()
+		ServeReviewing(cfg, rec, req, "Project", "001-AB-SUB-0001")
+
+		if rec.Code != http.StatusOK {
+			t.Fatalf("status=%d, body=%s", rec.Code, rec.Body.String())
+		}
+		var got []listing.FileInfo
+		if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+			t.Fatalf("decode: %v", err)
+		}
+		if len(got) != 1 || got[0].Name != "received/" {
+			t.Fatalf("got %+v, want [received/] only (no draft)", got)
+		}
+	})
+
+	t.Run("depth-1 unknown tracking → 404", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/Project/reviewing/999-ZZ-SUB-9999/", nil)
+		req.Header.Set("Accept", "application/json")
+		req = req.WithContext(WithEmail(req.Context(), "alice@example.com"))
+		rec := httptest.NewRecorder()
+		ServeReviewing(cfg, rec, req, "Project", "999-ZZ-SUB-9999")
+		if rec.Code != http.StatusNotFound {
+			t.Errorf("status=%d, want 404", rec.Code)
+		}
+	})
+
+	t.Run("missing archive/ entirely → empty depth-0 listing", func(t *testing.T) {
+		// Fresh project state: no archive/ subtree at all.
+		bareRoot := t.TempDir()
+		mustWrite(t, filepath.Join(bareRoot, ".zddc"),
+			"acl:\n  permissions:\n    \"*\": rwcda\n")
+		mustMkdir(t, filepath.Join(bareRoot, "Fresh"))
+		zddc.InvalidateCache(bareRoot)
+		bareCfg := config.Config{Root: bareRoot, EmailHeader: "X-Auth-Request-Email"}
+
+		req := httptest.NewRequest(http.MethodGet, "/Fresh/reviewing/", nil)
+		req.Header.Set("Accept", "application/json")
+		req = req.WithContext(WithEmail(req.Context(), "alice@example.com"))
+		rec := httptest.NewRecorder()
+		ServeReviewing(bareCfg, rec, req, "Fresh", "")
+		if rec.Code != http.StatusOK {
+			t.Fatalf("status=%d, body=%s", rec.Code, rec.Body.String())
+		}
+		body := rec.Body.String()
+		// Empty array, not "null".
+		if body == "null" || body == "null\n" {
+			t.Errorf("body=%q, want []; nil-slice encoded as null", body)
+		}
+	})
+}
+
+// startsWith — local helper. mustMkdir / mustWrite live in
+// formhandler_test.go and are reused here.
+func startsWith(s, prefix string) bool {
+	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
+}