app/worker/src/cloudflareBackend.ts

 // The real Backend (engine/backend.ts) for one Durable Object instance

 // -- one DO per repo, folding together the three pieces proven

 // separately this session: Lane/Ask/Answer on this DO's own SQLite

 // storage, git content (reads native, writes via isomorphic-git's

 // minimal-object push) and the Ladder (git notes, via a scoped

 // isomorphic-git checkout of just the relevant notes ref) against the

 // real Artifacts repo. engine/lane.ts/engine/workqueue.ts never see

 // any of this directly -- they only ever call the Backend interface,

 // scoped into context via engine/backend.ts's withBackend().

 import type { Backend } from "../../engine/backend.js";

 import type { Lane } from "../../engine/types.js";

 import { REPO_RUNG_PATH, type Rung, type RungKind } from "../../engine/ladder.js";

 import type { EmbeddedRung as RealEmbeddedRung } from "../../engine/ladderNotes.js";

 import { resolveLadderTree, type ResolvedRung } from "../../engine/ladderRender.js";

 import type { CommitRow, FileChangeRow } from "../../engine/ingest.js";

 import type { ChangesetFile, CommitAuthor } from "../../engine/changeset.js";

 import { commitChangesetOnArtifacts, headOid, readFileAtCommit as readFileAtCommitImpl, type ArtifactsNamespace, type ArtifactsRepoHandle } from "./cloudflareGitBackend.js";

 import { writeRung, readRung, appendRepoChildren as appendRepoChildrenImpl, rootCommitOid, type SimpleRung, type NotesCache } from "./cloudflareLadderBackend.js";

 import { indexLadderRung, searchLadderIndex } from "./accountsDb.js";

 interface RepoInfo {

  remote: string;

 }

 async function withRepo<T>(artifacts: ArtifactsNamespace, name: string, fn: (repo: ArtifactsRepoHandle, remote: string) => Promise<T>): Promise<T> {

  const repo = await artifacts.get(name);

  try {

  const info = (await repo.info()) as RepoInfo;

  return await fn(repo, info.remote);

  } finally {

  repo[Symbol.dispose]?.();

  }

 }

 // Rung's real kind union is wider (directory/release/ask/contributor/

 // dependencies/...) than what cloudflareLadderBackend.ts implements

 // (repo/file/changeset/filechange, matching what agent/scriptedWork.ts

 // actually writes) -- this throws a clear, specific error for any

 // other kind rather than silently mishandling it.

 function toSimpleRung(rung: Rung): SimpleRung {

  const kind = rung.kind;

  if (kind !== "repo" && kind !== "file" && kind !== "changeset" && kind !== "filechange") {

  throw new Error(`CloudflareBackend: rung kind "${kind}" isn't implemented yet (only repo/file/changeset/filechange are -- see cloudflareLadderBackend.ts's header). Add it there the same way if something now writes it.`);

  }

  return {

  path: rung.path,

  kind,

  summary: rung.summary,

  sources: rung.sources.filter((s) => s.kind === "commit") as SimpleRung["sources"],

  children: rung.children.map(toSimpleRung),

  };

 }

 /** Every "file"/"repo" kind rung in the tree, in-memory only (a SimpleRung's children are already embedded inline, not a separate fetch per child) -- the set of things worth putting in the cross-repo search index. "changeset"/"filechange" are historical per-commit entries, not current-state descriptions, so they're skipped. */

 function collectSearchableRungs(rung: SimpleRung, out: SimpleRung[]): void {

  if (rung.kind === "file" || rung.kind === "repo") out.push(rung);

  for (const child of rung.children) collectSearchableRungs(child, out);

 }

 /** Same filter, over a resolveLadderTree()-resolved tree instead of a SimpleRung -- used by reindexLadder, which walks the Ladder as it reads back (refs followed, not embedded inline the way a fresh write's SimpleRung already is). */

 function collectSearchableResolvedRungs(rung: ResolvedRung, out: ResolvedRung[]): void {

  if (rung.kind === "file" || rung.kind === "repo") out.push(rung);

  for (const child of rung.children) collectSearchableResolvedRungs(child, out);

 }

 export function createCloudflareBackend(storage: DurableObjectStorage, artifacts: ArtifactsNamespace, artifactsName: string, db: D1Database): Backend {

  const sql = storage.sql;

  sql.exec("CREATE TABLE IF NOT EXISTS lanes (id TEXT PRIMARY KEY, data TEXT NOT NULL)");

  function readLaneSync(laneId: string): Lane | null {

  const row = sql.exec("SELECT data FROM lanes WHERE id = ?", laneId).toArray()[0] as { data: string } | undefined;

  return row ? (JSON.parse(row.data) as Lane) : null;

  }

  function writeLaneSync(lane: Lane): void {

  sql.exec("INSERT OR REPLACE INTO lanes (id, data) VALUES (?, ?)", lane.id, JSON.stringify(lane));

  }

  // The repo's root (first) commit never changes once a repo has any

  // history -- every later commit only extends the chain forward, so

  // re-deriving it from scratch on every single "_repo" rung read

  // (rootCommitOid's own repo.log(limit:1000) fetch) was pure waste.

  // Confirmed live: this one call was the dominant cost of a repo

  // page's Ladder-tab fetch, well past what the zz-meta branch fetch

  // (webApp.ts's own earlier fix) cost on its own. Cached in this DO's

  // own durable storage, not an in-memory closure -- configure()

  // rebuilds this whole Backend object on every call, so a closure

  // variable would never survive past the request that set it.

  async function cachedRootCommitOid(repo: ArtifactsRepoHandle): Promise<string> {

  const cached = await storage.get<string>("rootCommitOid");

  if (cached) return cached;

  const oid = await rootCommitOid(repo);

  await storage.put("rootCommitOid", oid);

  return oid;

  }

  // Shared across every readAnchorFor call this Backend object

  // handles (i.e. for as long as this DO instance stays configured

  // for this one repo -- see MaintainerDO.configure, which only

  // rebuilds this whole Backend, and so this cache, on an actual repo

  // change). The Ladder tab's getLadderTree (webApp.ts) resolves the

  // "_repo" root's several top-level children (one DO call each) in

  // sequence without re-configuring in between, and several of those

  // children share the exact same underlying notes ref (every

  // file/directory/function/lines rung uses the one "code" ref) --

  // without this, each of those calls re-ran scopedNotesCheckout's

  // real git fetch of that identical ref from scratch. Confirmed live:

  // for a repo with 3 files + 2 changesets at the top level, that was

  // 5 redundant checkouts instead of 2.

  const notesCache: NotesCache = new Map();

  // The WHOLE resolved tree, cached durably and kept up to date on

  // every write (writeLadder below, via mergeRungsIntoLadderTreeCache)

  // -- not time-based, so a repo nobody's touching stays servable from

  // cache indefinitely. Durable storage, not an in-memory field, so it

  // survives this DO instance being evicted and cold-starting later --

  // the in-memory notesCache above only needs to survive one burst of

  // calls (it's just dedup within a resolve), but this is the actual

  // "don't make a user wait on N real git-notes fetches to see an

  // unchanged Ladder tab" fix, so it should outlive the JS instance,

  // not just one request. Direct instruction: "cache at every level

  // and invalidate cache only on ladder updates so that it can be

  // warmed" -- this is that cache, updated (not merely invalidated)

  // on every update so it's never left cold right when it matters

  // most: a brand-new write's own notes aren't reliably readable back

  // from Artifacts for a while after (readRung's doc comment has the

  // full story) -- updating the cache directly from the rungs already

  // in hand sidesteps that gap instead of racing it.

  const LADDER_TREE_CACHE_KEY = "resolvedLadderTree";

  function simpleToResolved(rung: SimpleRung): ResolvedRung {

  return { path: rung.path, kind: rung.kind, summary: rung.summary, sources: rung.sources, children: rung.children.map(simpleToResolved) };

  }

  // Builds/updates the cached tree directly from the rungs just

  // written -- no re-read from Artifacts at all, so this can't be

  // caught by the same-ref read-after-write gap readRung's doc

  // comment describes (confirmed live: even re-resolving through the

  // SAME repo handle/token the write itself just used still couldn't

  // see a brand-new ref moments after creating it). A "_repo" write

  // only replaces root's own fields and keeps whatever children the

  // cache already had -- a root rung's own `children` is always []

  // from the caller (engine/lane.ts's mergeLaneLadder writes _repo's

  // real children via the separate appendRepoChildren call), so

  // overwriting children here would just erase them. A non-root rung

  // is upserted directly as a child of root: that's also exactly

  // where appendRepoChildren would otherwise be linking it, and

  // mergeLaneLadder always calls writeLadder then appendRepoChildren

  // with the very same rungs in the same merge -- doing it here makes

  // appendRepoChildren's own cache step unnecessary for that one real

  // call pattern, so it's left alone instead of risking an

  // Artifacts-read-based refresh clobbering a cache this already got

  // right.

  async function mergeRungsIntoLadderTreeCache(rungs: SimpleRung[]): Promise<void> {

  let tree = (await storage.get<ResolvedRung>(LADDER_TREE_CACHE_KEY)) ?? null;

  for (const rung of rungs) {

  if (rung.path === REPO_RUNG_PATH) {

  tree = tree ? { ...simpleToResolved(rung), children: tree.children } : simpleToResolved(rung);

  continue;

  }

  // No root to attach to yet, and this write isn't the root

  // either -- leave the cache alone; a later real read recomputes

  // from Artifacts the old way rather than caching a rootless tree.

  if (!tree) continue;

  const node = simpleToResolved(rung);

  const idx = tree.children.findIndex((c) => c.path === rung.path);

  tree = idx >= 0 ? { ...tree, children: tree.children.map((c, i) => (i === idx ? node : c)) } : { ...tree, children: [...tree.children, node] };

  }

  if (tree) await storage.put(LADDER_TREE_CACHE_KEY, tree);

  }

  // Extracted out of the `readAnchor` method itself so reindexLadder

  // (below) can drive the same path-resolution logic through

  // resolveLadderTree without going through `this` -- a plain closure,

  // not a bound method, so it stays correct regardless of how this

  // Backend object gets passed around.

  async function readAnchorFor(path: string): Promise<RealEmbeddedRung | null> {

  return withRepo(artifacts, artifactsName, async (repo, remote) => {

  const token = await repo.createToken("read", 3600);

  // "repo" for the root path. A changeset is anchored by commit

  // sha, not a tree path -- readRung's `explicitAnchorSha` param

  // exists for exactly this, but needs a real sha from somewhere.

  // The established path convention (agent/tools.ts's

  // VALID_RUNG_EXAMPLE, cli/commands/work.ts's own comment) is

  // "changesets/<full commit sha>", so the sha is sitting right

  // there in the path itself -- no index file needed, unlike the

  // local backend's stateDir-based one (engine/ladderNotes.ts).

  // Confirmed live: before this, a changeset rung could be

  // written (writeLadder/toSimpleRung handle "changeset" fine)

  // but never read back through this path -- readAnchor always

  // fell through to "file", which tried to resolve the path as a

  // real tree entry and failed ("not found in the repo at HEAD").

  if (path === "_repo") {

  return (await readRung(remote, token, repo, "repo", path, await cachedRootCommitOid(repo), notesCache)) as RealEmbeddedRung | null;

  }

  if (path.startsWith("changesets/")) {

  const sha = path.slice("changesets/".length);

  return (await readRung(remote, token, repo, "changeset", path, sha, notesCache)) as RealEmbeddedRung | null;

  }

  return (await readRung(remote, token, repo, "file", path, undefined, notesCache)) as RealEmbeddedRung | null;

  });

  }

  return {

  name: "cloudflare",

  async ensureCloned(): Promise<void> {

  // No-op: the Artifacts repo is assumed to already exist by the

  // time any DO method runs against it (created once, out of

  // band, the same moment a local repo's first `zz work` call

  // would `ensureCloned` it) -- there's no "local" here to clone

  // into regardless.

  },

  async listCommits(): Promise<CommitRow[]> {

  return withRepo(artifacts, artifactsName, async (repo) => {

  const history = await repo.log({ ref: "main", limit: 1000 });

  // Native log() returns newest-first; engine/ingest.ts's real

  // listCommitsChronological (and everything built on it) expects

  // oldest-first, matching `git log --reverse`.

  return history

  .slice()

  .reverse()

  .map((c) => ({ sha: c.hash, parent: c.parents[0] ?? null, author: c.author?.name ?? "", at: new Date(c.authoredAt * 1000).toISOString(), message: c.message }));

  });

  },

  async diffCommit(_repo, commit: CommitRow): Promise<FileChangeRow[]> {

  // Tree-level diff only (added/modified/deleted) -- no line-level

  // hunks, since there's no `git diff` here, only native tree

  // reads (readCommit/readTree). Not exercised by the live agent

  // loop today (git_diff is a read-only exploration tool); a real

  // limitation flagged rather than silently guessed at if that

  // changes -- line-level hunks would need either a real

  // isomorphic-git diff (a clone) or a hand-rolled line differ,

  // neither built here.

  return withRepo(artifacts, artifactsName, async (repo) => {

  const c = await repo.readCommit(commit.sha);

  if (!c) return [];

  const tree = (await repo.readTree(c.treeHash)) ?? [];

  if (!commit.parent) return tree.map((e) => ({ path: e.name, status: "added" as const, hunks: [] }));

  const parentCommit = await repo.readCommit(commit.parent);

  const parentTree = parentCommit ? (await repo.readTree(parentCommit.treeHash)) ?? [] : [];

  const parentByName = new Map(parentTree.map((e) => [e.name, e]));

  const curByName = new Map(tree.map((e) => [e.name, e]));

  const rows: FileChangeRow[] = [];

  for (const [name, entry] of curByName) {

  const before = parentByName.get(name);

  if (!before) rows.push({ path: name, status: "added", hunks: [] });

  else if (before.hash !== entry.hash) rows.push({ path: name, status: "modified", hunks: [] });

  }

  for (const name of parentByName.keys()) {

  if (!curByName.has(name)) rows.push({ path: name, status: "deleted", hunks: [] });

  }

  return rows;

  });

  },

  async readFileAtCommit(_repo, sha: string, path: string): Promise<string> {

  // "HEAD" is part of the Backend contract, not a real sha --

  // engine/localBackend.ts honors it for free by shelling out to

  // real git (`git show HEAD:path`); the native Artifacts binding

  // only accepts a literal 40-char sha, so resolve it here first

  // (confirmed live: agent/tools.ts's checkNoDroppedExports calls

  // this with sha="HEAD" on every commit_changeset).

  return withRepo(artifacts, artifactsName, async (repo) => readFileAtCommitImpl(repo, sha === "HEAD" ? await headOid(repo) : sha, path));

  },

  async commitChangeset(_repo, input: { files: ChangesetFile[]; message: string; author: CommitAuthor }): Promise<string> {

  return withRepo(artifacts, artifactsName, async (repo, remote) => {

  const token = await repo.createToken("write", 3600);

  return commitChangesetOnArtifacts(artifactsName, remote, token, repo, input);

  });

  },

  async readAnchor(_repo, path: string): Promise<RealEmbeddedRung | null> {

  return readAnchorFor(path);

  },

  // The one real fix for "the Ladder tab/zz top is slow" -- see

  // engine/backend.ts's own doc comment on this method for why a

  // Cloudflare-backed repo needs this where LocalBackend doesn't.

  // Cache-first: a cache hit is one durable-storage read, no

  // Artifacts/git calls at all, regardless of how many rungs the

  // real tree has.

  async readLadderTree(): Promise<ResolvedRung | null> {

  const cached = await storage.get<ResolvedRung>(LADDER_TREE_CACHE_KEY);

  if (cached) return cached;

  const { tree } = await resolveLadderTree(readAnchorFor);

  await storage.put(LADDER_TREE_CACHE_KEY, tree);

  return tree;

  },

  async writeLadder(_repo, rung: Rung | Rung[]): Promise<void> {

  const rungs = (Array.isArray(rung) ? rung : [rung]).map(toSimpleRung);

  await withRepo(artifacts, artifactsName, async (repo, remote) => {

  const token = await repo.createToken("write", 3600);

  for (const one of rungs) await writeRung(remote, token, repo, one);

  });

  // Built directly from the rungs just written -- see

  // mergeRungsIntoLadderTreeCache's doc comment for why this

  // doesn't re-read from Artifacts to do it.

  await mergeRungsIntoLadderTreeCache(rungs);

  // Index after the real write succeeds, not before -- a search

  // hit should never point at content that didn't actually land.

  const searchable: SimpleRung[] = [];

  for (const one of rungs) collectSearchableRungs(one, searchable);

  for (const one of searchable) {

  // The most recent commit source, not the first -- sources

  // accumulates chronologically as a file gets touched again, and

  // a search result's commit link should point at what most

  // recently shaped this summary, not its very first appearance.

  const commitSha = one.sources.length ? one.sources[one.sources.length - 1].ref : null;

  await indexLadderRung(db, artifactsName, one.path, one.kind, one.summary, commitSha);

  }

  },

  async appendRepoChildren(_repo, children: { path: string; kind: RungKind }[]): Promise<void> {

  await withRepo(artifacts, artifactsName, async (repo, remote) => {

  const token = await repo.createToken("write", 3600);

  await appendRepoChildrenImpl(remote, token, repo, children);

  });

  // No cache update needed here: the one real caller

  // (engine/lane.ts's mergeLaneLadder) always calls writeLadder

  // with these exact same rungs immediately before this, and that

  // call's own mergeRungsIntoLadderTreeCache already added them

  // as children of root -- this call is just linking the same

  // refs on the Artifacts side. If that stops being true for some

  // future caller, this would need its own merge or an

  // invalidateLadderTreeCache() fallback; not needed today.

  },

  async searchLadder(query, limit) {

  const hits = await searchLadderIndex(db, query, limit, null);

  return hits.map((h) => ({ repo: h.repo_slug, path: h.path, kind: h.kind as RungKind, commitSha: h.commit_sha, summary: h.summary }));

  },

  // Backfill: searchLadder only ever sees what's been written SINCE

  // the index existed (confirmed live: a repo with real "tie"/"untie"

  // content in a file rung written before this feature shipped was

  // invisible to search -- only a repo's newest written rung showed

  // up). Walks the repo's current tree the same way the read path

  // does (resolveLadderTree + this backend's own anchor resolution,

  // following every ref) rather than trusting whatever's already

  // embedded in one note, so a rung that's only reachable via a ref

  // chain still gets (re)indexed correctly.

  async reindexLadder(): Promise<number> {

  const { tree } = await resolveLadderTree(readAnchorFor);

  const searchable: ResolvedRung[] = [];

  collectSearchableResolvedRungs(tree, searchable);

  for (const one of searchable) {

  const commitSources = one.sources.filter((s) => s.kind === "commit");

  const commitSha = commitSources.length ? commitSources[commitSources.length - 1].ref : null;

  await indexLadderRung(db, artifactsName, one.path, one.kind, one.summary, commitSha);

  }

  return searchable.length;

  },

  async readLane(_repo, laneId: string): Promise<Lane | null> {

  return readLaneSync(laneId);

  },

  async writeLane(_repo, lane: Lane): Promise<void> {

  writeLaneSync(lane);

  },

  async listLanes(): Promise<Lane[]> {

  return sql

  .exec("SELECT data FROM lanes")

  .toArray()

  .map((r) => JSON.parse((r as { data: string }).data) as Lane);

  },

  async withLane(_repo, laneId: string, mutate: (lane: Lane) => void): Promise<Lane> {

  return storage.transactionSync(() => {

  const lane = readLaneSync(laneId);

  if (!lane) throw new Error(`no such lane: ${laneId}`);

  mutate(lane);

  writeLaneSync(lane);

  return lane;

  });

  },

  };

 }