feat(environment): list every entity on a list's whole lines (#5787)

Derive whole-collection membership per checked list line while preserving
recorded membership, counters, source Evidence and independent write claims.

Integrate current main without losing its shared path decoder. Keep later or
ambiguously positioned pages recorded rather than inventing earlier entities.

Validation: 543 focused/adjacent tests, nine README checks, complete static/docs
checks, repeated regression runs, and real retained GitHub-label CLI/MCP
load/reset workflows. An actual Codex session returned the correct facts;
its over-strict grader failure and same-trace semantic verification are recorded.

Evidence and limitations:
https://github.com/morluto/rea/pull/5787#issuecomment-6338446674
Tracking: #6262; feature scope: #4933.

Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)

src/application/environment/environmentStateWriteAnswer.test.ts

@@ -10,10 +10,12 @@ import {
   BOOK_ROWS,
   DELETE_NOT_FOUND,
   FIRST_BOOK,
+  LIST_LINE_ROWS,
   SECOND_BOOK,
   THIRD_BOOK,
   book,
   bookClock,
+  bookPage,
   renamedBook,
   type Book,
 } from "../../../tests/fixtures/environmentStateWrites.js";
@@ -539,6 +541,97 @@ describe("paged list lines", () => {
   });
 });
 
+describe("list lines", () => {
+  it("keeps an empty later page recorded after data/add, while a first line lists the loaded entity", () => {
+    for (const [query, whole] of [
+      ["offset=0", true],
+      ["start=0", true],
+      ["_start=0", true],
+      ["page=0", true],
+      ["offset=2", false],
+      ["start=2", false],
+      ["_start=2", false],
+      ["page=1", false],
+      ["offset=-1", false],
+      ["offset=unknown", false],
+    ] as const) {
+      const alpha = { id: 1, name: "Alpha", org: "1" };
+      const beta = { id: 2, name: "Beta", org: "2" };
+      const books = servedFrom([
+        ["GET", "/api/orgs/1/books", [alpha]],
+        ["GET", "/api/orgs/1/books?name=Alpha", [alpha]],
+        ["GET", `/api/orgs/2/books?${query}&limit=50`, []],
+        ["GET", "/api/orgs/1/books/1", alpha],
+      ]);
+      const held = books.store.snapshot().rea_state;
+      const loaded = books.store.replace({
+        rea_state: {
+          ...held,
+          entities: [
+            ...held.entities,
+            {
+              type: held.entities[0]!.type,
+              collection: "/api/orgs/2/books",
+              id: "2",
+              fields: beta,
+              view_fields: [],
+              record_ordinals: [],
+            },
+          ],
+        },
+      });
+      if (!loaded.ok) throw loaded.error;
+      expect(
+        books.answer("get_orgs_books_by_id", {
+          id: "2",
+          ...Object.fromEntries(new URLSearchParams(query)),
+          limit: "50",
+        }),
+      ).toMatchObject({
+        body: whole ? [beta] : [],
+        state: {
+          source: "state",
+          membership: whole ? "all" : "recorded",
+          listed: whole ? 1 : 0,
+        },
+      });
+    }
+  });
+
+  it("lists a created book on the line that lists every book, while a filtered line keeps its recorded members", () => {
+    const books = servedFrom(LIST_LINE_ROWS);
+    const created = books.answer("post_books", CREATE_NEW_BOOK).body as Book;
+    expect(books.answer("get_books")).toMatchObject({
+      body: bookPage([FIRST_BOOK, SECOND_BOOK, created]),
+      state: { source: "state", membership: "all", listed: 3 },
+    });
+    expect(books.answer("get_books", { name: "First Book" })).toMatchObject({
+      body: bookPage([FIRST_BOOK]),
+      state: { source: "state", membership: "recorded", listed: 1 },
+    });
+  });
+
+  it("updates on each line only the counters its recording counted, so a partial page keeps its total", () => {
+    const partial = {
+      content: [FIRST_BOOK],
+      totalElements: 2,
+      numberOfElements: 1,
+    };
+    const books = servedFrom([
+      ["GET", "/api/books", bookPage([FIRST_BOOK, SECOND_BOOK])],
+      ["GET", "/api/books?page=1&size=1", partial],
+      ...LIST_LINE_ROWS.slice(2),
+    ]);
+    const created = books.answer("post_books", CREATE_NEW_BOOK).body as Book;
+    expect(books.answer("get_books")).toMatchObject({
+      body: bookPage([FIRST_BOOK, SECOND_BOOK, created]),
+    });
+    expect(books.answer("get_books", { page: "1", size: "1" })).toMatchObject({
+      body: partial,
+    });
+  });
+});
+
 describe("path values", () => {
   const orgBook = (id: number, org: string, name: string): Book => ({
     id,