diff --git a/apps/web/src/components/sections-editor/schemaless.test.ts b/apps/web/src/components/sections-editor/schemaless.test.ts
new file mode 100644
index 0000000000..865397ad18
--- /dev/null
+++ b/apps/web/src/components/sections-editor/schemaless.test.ts
@@ -0,0 +1,136 @@
+import { describe, expect, it } from "bun:test";
+import { ContentProtocolError, ErrorCode } from "@decocms/blocks/protocol";
+import {
+  groupBlocksByType,
+  isNoSchemaMeta,
+  isSchemaAbsent,
+  noSchemaMeta,
+  parseNumberInput,
+  setAtPath,
+  typeLabel,
+} from "./schemaless";
+
+describe("isSchemaAbsent", () => {
+  it("reads schema: null and an older server's NotFound as no schema", () => {
+    expect(
+      isSchemaAbsent({
+        ok: true,
+        result: {
+          notModified: false,
+          version: null,
+          resolvedRef: null,
+          schema: null,
+        },
+      }),
+    ).toBe(true);
+    expect(
+      isSchemaAbsent({
+        ok: false,
+        error: new ContentProtocolError(ErrorCode.NotFound, "no schema"),
+      }),
+    ).toBe(true);
+  });
+
+  it("is false for a schema, a 'not modified' and any other error", () => {
+    expect(
+      isSchemaAbsent({
+        ok: true,
+        result: {
+          notModified: false,
+          version: "v1",
+          resolvedRef: null,
+          schema: {},
+        },
+      }),
+    ).toBe(false);
+    expect(
+      isSchemaAbsent({
+        ok: true,
+        result: { notModified: true, version: "v1" },
+      }),
+    ).toBe(false);
+    expect(
+      isSchemaAbsent({
+        ok: false,
+        error: new ContentProtocolError(ErrorCode.Unavailable, "busy"),
+      }),
+    ).toBe(false);
+  });
+});
+
+describe("noSchemaMeta", () => {
+  it("is an empty schema the editor can tell apart", () => {
+    const meta = noSchemaMeta();
+    expect(meta.manifest.blocks).toEqual({});
+    expect(isNoSchemaMeta(meta)).toBe(true);
+    expect(isNoSchemaMeta({ manifest: { blocks: {} }, schema: {} })).toBe(
+      false,
+    );
+    expect(isNoSchemaMeta(undefined)).toBe(false);
+  });
+});
+
+describe("groupBlocksByType", () => {
+  it("groups every block by __resolveType, sorted by name, untyped last", () => {
+    const groups = groupBlocksByType({
+      "pages-home": { __resolveType: "website/pages/Page.tsx", name: "Home" },
+      "pages-about": { __resolveType: "website/pages/Page.tsx", name: "About" },
+      Header: { __resolveType: "site/sections/Header.tsx" },
+      loose: { title: "no type" },
+    });
+    expect(groups).toEqual([
+      {
+        resolveType: "site/sections/Header.tsx",
+        blocks: [{ key: "Header", label: "Header" }],
+      },
+      {
+        resolveType: "website/pages/Page.tsx",
+        blocks: [
+          { key: "pages-about", label: "About" },
+          { key: "pages-home", label: "Home" },
+        ],
+      },
+      { resolveType: null, blocks: [{ key: "loose", label: "loose" }] },
+    ]);
+  });
+
+  it("names a type by its last path segment", () => {
+    expect(typeLabel("site/sections/Header.tsx")).toBe("Header");
+    expect(typeLabel("website/loaders/redirects.ts")).toBe("redirects");
+  });
+});
+
+describe("setAtPath", () => {
+  it("replaces one leaf and keeps every other value and the key order", () => {
+    const block = {
+      __resolveType: "site/sections/Hero.tsx",
+      title: "Hi",
+      items: [
+        { n: 1, on: true },
+        { n: 2, on: false },
+      ],
+      nested: { a: null, b: "x" },
+    };
+    const next = setAtPath(block, ["items", 1, "n"], 3);
+    expect(JSON.stringify(next)).toBe(
+      JSON.stringify({
+        ...block,
+        items: [
+          { n: 1, on: true },
+          { n: 3, on: false },
+        ],
+      }),
+    );
+    // The original is untouched.
+    expect(block.items[1]!.n).toBe(2);
+  });
+});
+
+describe("parseNumberInput", () => {
+  it("reads finite numbers only", () => {
+    expect(parseNumberInput("42")).toBe(42);
+    expect(parseNumberInput("-1.5")).toBe(-1.5);
+    expect(parseNumberInput("")).toBeNull();
+    expect(parseNumberInput("4a")).toBeNull();
+  });
+});
diff --git a/apps/web/src/components/sections-editor/schemaless.ts b/apps/web/src/components/sections-editor/schemaless.ts
new file mode 100644
index 0000000000..dbee54f257
--- /dev/null
+++ b/apps/web/src/components/sections-editor/schemaless.ts
@@ -0,0 +1,137 @@
+/**
+ * A Blocks site whose schema isn't generated yet (`deco schema` hasn't run).
+ *
+ * The content protocol still lists and saves every block without a schema;
+ * only the typed forms need it. The editor reads "no schema" as an empty
+ * schema carrying a marker (`noSchemaMeta`), so the poll keeps one shape and
+ * the real schema replaces it on its own once it appears. Surfaces that would
+ * otherwise build forms from the schema show the blocks grouped by type and a
+ * form inferred from each block's JSON instead.
+ *
+ * Pure: unit-tested without mocks.
+ */
+
+import { type BatchOutcome, ErrorCode } from "@decocms/blocks/protocol";
+import type { LiveMeta } from "./resolve-schema";
+
+const NO_SCHEMA_MARKER = "__noSchema";
+
+/** The schema of a site with none yet: empty, and marked as such. */
+export function noSchemaMeta(): LiveMeta {
+  return {
+    manifest: { blocks: {} },
+    schema: { definitions: {}, root: {} },
+    [NO_SCHEMA_MARKER]: true,
+  } as LiveMeta;
+}
+
+/** Whether `meta` stands in for a site with no schema yet. */
+export function isNoSchemaMeta(meta: LiveMeta | null | undefined): boolean {
+  return (
+    !!meta &&
+    (meta as unknown as Record<string, unknown>)[NO_SCHEMA_MARKER] === true
+  );
+}
+
+/**
+ * Whether a `schema.get` outcome says there's no schema yet: `schema: null`,
+ * or NotFound from a `deco serve` older than that result.
+ */
+export function isSchemaAbsent(outcome: BatchOutcome): boolean {
+  if (!outcome.ok) return outcome.error.code === ErrorCode.NotFound;
+  const result = outcome.result as { notModified?: boolean; schema?: unknown };
+  return result.notModified === false && result.schema === null;
+}
+
+export interface SchemalessBlock {
+  key: string;
+  label: string;
+}
+
+export interface SchemalessGroup {
+  /** The blocks' `__resolveType`; `null` for blocks without one. */
+  resolveType: string | null;
+  blocks: SchemalessBlock[];
+}
+
+function blockLabel(key: string, block: Record<string, unknown>): string {
+  const name = typeof block.name === "string" ? block.name.trim() : "";
+  return name || key;
+}
+
+const byLabel = (a: SchemalessBlock, b: SchemalessBlock) =>
+  a.label.localeCompare(b.label) || a.key.localeCompare(b.key);
+
+/** Every saved block, grouped by `__resolveType` and sorted by name. */
+export function groupBlocksByType(
+  decofile: Record<string, unknown>,
+): SchemalessGroup[] {
+  const groups = new Map<string | null, SchemalessBlock[]>();
+  for (const [key, value] of Object.entries(decofile)) {
+    const block =
+      value && typeof value === "object" && !Array.isArray(value)
+        ? (value as Record<string, unknown>)
+        : {};
+    const resolveType =
+      typeof block.__resolveType === "string" ? block.__resolveType : null;
+    const list = groups.get(resolveType) ?? [];
+    list.push({ key, label: blockLabel(key, block) });
+    groups.set(resolveType, list);
+  }
+  return [...groups.entries()]
+    .map(([resolveType, blocks]) => ({
+      resolveType,
+      blocks: blocks.sort(byLabel),
+    }))
+    .sort((a, b) =>
+      a.resolveType === null
+        ? 1
+        : b.resolveType === null
+          ? -1
+          : typeLabel(a.resolveType).localeCompare(typeLabel(b.resolveType)) ||
+            a.resolveType.localeCompare(b.resolveType),
+    );
+}
+
+/** `site/sections/Header.tsx` → `Header`. */
+export function typeLabel(resolveType: string): string {
+  const last = resolveType.split("/").filter(Boolean).at(-1) ?? resolveType;
+  return last.replace(/\.(tsx?|jsx?)$/, "") || resolveType;
+}
+
+export type JsonPath = readonly (string | number)[];
+
+/**
+ * `value` with the leaf at `path` replaced; everything else, key order
+ * included, stays exactly as it was.
+ */
+export function setAtPath(
+  value: unknown,
+  path: JsonPath,
+  leaf: unknown,
+): unknown {
+  if (path.length === 0) return leaf;
+  const [head, ...rest] = path;
+  if (Array.isArray(value) && typeof head === "number") {
+    const next = value.slice();
+    next[head] = setAtPath(value[head], rest, leaf);
+    return next;
+  }
+  if (value && typeof value === "object" && typeof head === "string") {
+    const record = value as Record<string, unknown>;
+    const next: Record<string, unknown> = {};
+    for (const key of Object.keys(record)) {
+      next[key] =
+        key === head ? setAtPath(record[key], rest, leaf) : record[key];
+    }
+    return next;
+  }
+  return value;
+}
+
+/** A number typed into a field, or `null` while it isn't one yet. */
+export function parseNumberInput(text: string): number | null {
+  if (text.trim() === "") return null;
+  const parsed = Number(text);
+  return Number.isFinite(parsed) ? parsed : null;
+}