diff --git a/zddc/cmd/zddc-server/main.go b/zddc/cmd/zddc-server/main.go
index 3828c55..0e3d1ef 100644
--- a/zddc/cmd/zddc-server/main.go
+++ b/zddc/cmd/zddc-server/main.go
@@ -796,6 +796,13 @@ func dispatch(cfg config.Config, idx *archive.Index, ring *handler.LogRing, apps
 		return
 	}
 
+	// The .zddc JSON Schema (machine grammar) — drives the .zddc form view +
+	// client validation. Static, read-only, no auth.
+	if urlPath == handler.ZddcSchemaPath {
+		handler.ServeZddcSchema(w, r)
+		return
+	}
+
 	// Auth check endpoints — machine-only forward_auth targets used by
 	// upstream proxies (e.g. the dev-shell pod's Caddy in front of
 	// code-server) to gate routes on root-admin status. Handled before
diff --git a/zddc/internal/handler/schemahandler.go b/zddc/internal/handler/schemahandler.go
new file mode 100644
index 0000000..f219e96
--- /dev/null
+++ b/zddc/internal/handler/schemahandler.go
@@ -0,0 +1,28 @@
+package handler
+
+import (
+	"net/http"
+
+	"codeberg.org/VARASYS/ZDDC/zddc/internal/zddc"
+)
+
+// ZddcSchemaPath is the JSON endpoint serving the .zddc JSON Schema (the machine
+// grammar). The browse client + the .zddc form view fetch it to drive editing
+// (per-property x-zddc-tier marks structure vs option) and validation.
+const ZddcSchemaPath = "/.api/zddc-schema"
+
+// ServeZddcSchema returns the embedded .zddc JSON Schema. Read-only, no auth —
+// it documents the policy grammar and leaks nothing. GET/HEAD only.
+func ServeZddcSchema(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet && r.Method != http.MethodHead {
+		w.Header().Set("Allow", "GET, HEAD")
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	w.Header().Set("Content-Type", "application/schema+json; charset=utf-8")
+	w.Header().Set("Cache-Control", "max-age=300")
+	if r.Method == http.MethodHead {
+		return
+	}
+	_, _ = w.Write(zddc.ZddcSchemaBytes())
+}
diff --git a/zddc/internal/zddc/schema.go b/zddc/internal/zddc/schema.go
new file mode 100644
index 0000000..501c17b
--- /dev/null
+++ b/zddc/internal/zddc/schema.go
@@ -0,0 +1,20 @@
+package zddc
+
+import _ "embed"
+
+// schemaBytes is the embedded .zddc JSON Schema (draft 2020-12). The
+// authoritative machine grammar: it drives the form view (per-property
+// x-zddc-tier: structure|option decides editable vs read-only) and client
+// validation. Server-side structural validation still lives in validate.go —
+// this schema uses $ref + patternProperties, which the in-tree
+// internal/jsonschema validator does not yet support.
+//
+//go:embed zddc.schema.json
+var schemaBytes []byte
+
+// ZddcSchemaBytes returns a copy of the embedded .zddc JSON Schema.
+func ZddcSchemaBytes() []byte {
+	out := make([]byte, len(schemaBytes))
+	copy(out, schemaBytes)
+	return out
+}
diff --git a/zddc/internal/zddc/schema_test.go b/zddc/internal/zddc/schema_test.go
new file mode 100644
index 0000000..b076ac9
--- /dev/null
+++ b/zddc/internal/zddc/schema_test.go
@@ -0,0 +1,59 @@
+package zddc
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+// The embedded .zddc schema must be valid JSON, cover the grammar's keys, and
+// tag every property structure|option — the contract the form view relies on.
+func TestZddcSchemaTiers(t *testing.T) {
+	var doc struct {
+		Properties map[string]struct {
+			Tier string `json:"x-zddc-tier"`
+		} `json:"properties"`
+	}
+	if err := json.Unmarshal(ZddcSchemaBytes(), &doc); err != nil {
+		t.Fatalf("schema is not valid JSON: %v", err)
+	}
+	if len(doc.Properties) == 0 {
+		t.Fatal("schema has no properties")
+	}
+
+	// Every property carries a valid tier.
+	for name, p := range doc.Properties {
+		if p.Tier != "structure" && p.Tier != "option" {
+			t.Errorf("property %q has x-zddc-tier=%q, want structure|option", name, p.Tier)
+		}
+	}
+
+	// Spot-check the classification the form depends on.
+	wantTier := map[string]string{
+		"roles":           "option", // who's in a group — the headline customisation
+		"field_codes":     "option",
+		"convert":         "option",
+		"display":         "option",
+		"admins":          "option",
+		"title":           "option",
+		"paths":           "structure", // the project shape
+		"worm":            "structure",
+		"party_source":    "structure",
+		"default_tool":    "structure",
+		"available_tools": "structure",
+		"auto_own":        "structure",
+		"acl":             "structure",
+		"records":         "structure",
+		"views":           "structure",
+		"created_by":      "structure",
+	}
+	for name, want := range wantTier {
+		p, ok := doc.Properties[name]
+		if !ok {
+			t.Errorf("schema missing expected key %q", name)
+			continue
+		}
+		if p.Tier != want {
+			t.Errorf("key %q tier=%q, want %q", name, p.Tier, want)
+		}
+	}
+}
diff --git a/zddc/internal/zddc/zddc.schema.json b/zddc/internal/zddc/zddc.schema.json
new file mode 100644
index 0000000..b14438f
--- /dev/null
+++ b/zddc/internal/zddc/zddc.schema.json
@@ -0,0 +1,203 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://zddc.varasys.io/schema/zddc.schema.json",
+  "title": ".zddc policy document",
+  "description": "Machine schema for the .zddc grammar (see GRAMMAR.md). Each property carries x-zddc-tier: 'structure' (the project shape an end user should not change — paths, WORM, tools, behaviors) or 'option' (the blanks an operator fills — role members, field-code vocabularies, names, labels). A form view renders option fields editable and structure fields read-only. NOTE: not all keys are valid at every level; the cascade + the per-location form decide relevance. Server-side validation still lives in validate.go (this draft-2020-12 schema uses $ref + patternProperties, which the in-tree validator does not yet support); the schema drives the form + client today.",
+  "type": "object",
+  "additionalProperties": false,
+  "properties": {
+    "title": {
+      "type": "string",
+      "description": "Human title for this directory.",
+      "x-zddc-tier": "option"
+    },
+    "created_by": {
+      "type": "string",
+      "description": "Email of the user who created this folder. Set by the server; audit only.",
+      "x-zddc-tier": "structure"
+    },
+    "admins": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "Principals (emails, globs, or role names) who administer this subtree. Root admins are super-admins; deeper entries are subtree admins. Elevation-gated full bypass over scope.",
+      "x-zddc-tier": "option"
+    },
+    "roles": {
+      "type": "object",
+      "description": "Named principal groups referenced by acl/worm/admins. Membership UNIONS across the cascade. The operator fills the members.",
+      "additionalProperties": {
+        "type": "object",
+        "additionalProperties": false,
+        "properties": {
+          "members": {
+            "type": "array",
+            "items": { "type": "string" },
+            "description": "Email patterns (alice@x, *@acme.com, *) in this role."
+          },
+          "reset": {
+            "type": "boolean",
+            "description": "Stop the membership union here: ancestor definitions above this level are excluded."
+          }
+        }
+      },
+      "x-zddc-tier": "option"
+    },
+    "acl": {
+      "type": "object",
+      "description": "Access control for this level. permissions maps a principal (email/glob/role) to a verb string from r w c d a (empty string = explicit deny). inherit:false clamps the ACL level-walk so ancestor levels' grants do not apply.",
+      "additionalProperties": false,
+      "properties": {
+        "inherit": { "type": "boolean", "description": "false = this level's ACL does not inherit ancestor levels." },
+        "permissions": {
+          "type": "object",
+          "patternProperties": {
+            "^.+$": { "type": "string", "pattern": "^[rwcda]*$", "description": "Verb subset of r w c d a; empty = explicit deny." }
+          },
+          "additionalProperties": false
+        }
+      },
+      "x-zddc-tier": "structure"
+    },
+    "worm": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "WORM zone: write/delete/admin stripped for all; create survives only for the listed principals; admins bypass. Unions across the cascade.",
+      "x-zddc-tier": "structure"
+    },
+    "inherit": {
+      "type": "boolean",
+      "description": "false = stop the cascade here; everything below (ancestors + embedded defaults) is ignored. Makes a subtree a self-contained island.",
+      "x-zddc-tier": "structure"
+    },
+    "default_tool": {
+      "type": "string",
+      "enum": ["archive", "transmittal", "classifier", "browse", "tables", "landing", "form"],
+      "description": "Tool served at <dir> (no trailing slash). Sugar for views.dir.tool.",
+      "x-zddc-tier": "structure"
+    },
+    "dir_tool": {
+      "type": "string",
+      "enum": ["archive", "transmittal", "classifier", "browse", "tables", "landing", "form"],
+      "description": "Tool served at <dir>/ (trailing slash). Sugar for views.dir_slash.tool; defaults to browse.",
+      "x-zddc-tier": "structure"
+    },
+    "views": {
+      "type": "object",
+      "description": "Per-URL-shape tool + supporting-config mapping.",
+      "additionalProperties": {
+        "type": "object",
+        "additionalProperties": false,
+        "properties": {
+          "tool": { "type": "string", "enum": ["archive", "transmittal", "classifier", "browse", "tables", "landing", "form"] },
+          "config": { "type": "string", "description": "Supporting-file name resolved under .zddc.d/ (no slashes)." }
+        }
+      },
+      "x-zddc-tier": "structure"
+    },
+    "available_tools": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "Tools the apps subsystem may auto-serve here and below. Concat-dedupe union across the cascade.",
+      "x-zddc-tier": "structure"
+    },
+    "auto_own": {
+      "type": "boolean",
+      "description": "mkdir here writes a creator-owned .zddc (creator: rwcda).",
+      "x-zddc-tier": "structure"
+    },
+    "auto_own_fenced": {
+      "type": "boolean",
+      "description": "The auto-own .zddc is written with acl.inherit:false (private to its creator).",
+      "x-zddc-tier": "structure"
+    },
+    "auto_own_roles": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "Roles also granted rwcda in the auto-own .zddc, alongside the creator.",
+      "x-zddc-tier": "structure"
+    },
+    "virtual": {
+      "type": "boolean",
+      "description": "Never materialise on disk; treat requests as virtual routes.",
+      "x-zddc-tier": "structure"
+    },
+    "drop_target": {
+      "type": "boolean",
+      "description": "This directory accepts drag-drop uploads (browse drop-zone). Leaf-only.",
+      "x-zddc-tier": "structure"
+    },
+    "party_source": {
+      "type": "string",
+      "description": "A new <party>/ here requires registration in <source>/<party>.yaml (e.g. 'ssr'). Leaf-only.",
+      "x-zddc-tier": "structure"
+    },
+    "history": {
+      "type": "boolean",
+      "description": "Snapshot text (markdown) edits to .history/ in this subtree with a server-stamped audit line.",
+      "x-zddc-tier": "structure"
+    },
+    "history_globs": {
+      "type": "array",
+      "items": { "type": "string" },
+      "description": "Which basenames get edit history (default [\"*.md\"]).",
+      "x-zddc-tier": "structure"
+    },
+    "convert": {
+      "type": "object",
+      "description": "Template variables for MD→{docx,html,pdf} conversion. Cascades leaf→root, per-key latest wins.",
+      "additionalProperties": false,
+      "properties": {
+        "client": { "type": "string" },
+        "project": { "type": "string" },
+        "contractor": { "type": "string" },
+        "project_number": { "type": "string" }
+      },
+      "x-zddc-tier": "option"
+    },
+    "field_codes": {
+      "type": "object",
+      "description": "Vocabularies for tracking-number / record field components. Map-merged per code across the cascade.",
+      "additionalProperties": { "type": "object" },
+      "x-zddc-tier": "option"
+    },
+    "records": {
+      "type": "object",
+      "description": "Per-record-type rules keyed by filename pattern (filename_format, field_defaults, locked, row_field, row_scope_fields, folder_fields).",
+      "additionalProperties": { "type": "object" },
+      "x-zddc-tier": "structure"
+    },
+    "display": {
+      "type": "object",
+      "description": "Human labels for child entries (on-disk name → label). Leaf-only.",
+      "additionalProperties": { "type": "string" },
+      "x-zddc-tier": "option"
+    },
+    "tables": {
+      "type": "object",
+      "description": "Legacy directory-of-YAML table views (stem → spec path).",
+      "additionalProperties": { "type": "string" },
+      "x-zddc-tier": "structure"
+    },
+    "received_path": {
+      "type": "string",
+      "description": "Links a workflow folder back to its canonical submittal in received/. Set by Plan Review.",
+      "x-zddc-tier": "structure"
+    },
+    "planned_review_date": {
+      "type": "string",
+      "description": "Doc-controller's committed review-completion date (YYYY-MM-DD), on the canonical submittal.",
+      "x-zddc-tier": "option"
+    },
+    "planned_response_date": {
+      "type": "string",
+      "description": "Doc-controller's committed response-issuance date (YYYY-MM-DD), on the canonical submittal.",
+      "x-zddc-tier": "option"
+    },
+    "paths": {
+      "type": "object",
+      "description": "Virtual sub-directory rules. Each key is a single path segment (literal or '*'); the value is a nested .zddc applied at the matching child directory. Recursive.",
+      "additionalProperties": { "$ref": "#" },
+      "x-zddc-tier": "structure"
+    }
+  }
+}