/**
 * storeRegistry — resolves (account, scope) → document NURI.
 *
 * Stopgap / polyfill-era. Emulates the target infrastructure — where each
 * user owns their own public/protected/private stores — on top of one shared
 * wallet. It creates one document per (account × scope) inside that shared
 * wallet (via the `docs.docCreate` primitive), so the `scope`
 * (`public|protected|private`) is a logical attribute tracked here, not a
 * physical NextGraph store. Isolation is enforced by the app layer + the
 * emulated cap registry, not by crypto.
 *
 * The mapping (account → its 3 document NURIs) is the **sharedWalletShim**. It
 * is persisted as RDF, but NOT in the store-root graph anymore — see the
 * indirection below. That makes login cross-device: another device opening the
 * same wallet reads the same shim and finds the same accounts.
 *
 * ── The indirection: pointer (store-root) → doc-shim (subscribable) ─────────
 * On the real NextGraph platform "findable-without-lookup" and "subscribable"
 * are DISJOINT (verified at the source, see docs/nextgraph-current-state.md
 * § *Findable vs subscribable*):
 *   - the ONLY NURI a fresh session can name WITHOUT a lookup is the store-root
 *     `did:ng:${privateStoreId}` — but a store-root has NO first-`State` sync
 *     BARRIER, so a cold "0 rows" on it is AMBIGUOUS (could be sync-lag, could
 *     be truly empty);
 *   - the ONLY thing that DOES have a first-`State` barrier is a `did:ng:o:<RepoID>`
 *     doc from `doc_create` — but its RepoID is RANDOM, so a fresh session
 *     cannot GUESS it; it must be looked up.
 * So a purely-barrier shim resolution is impossible: you cannot have a doc that
 * is both guessable and authoritative on a cold read. The indirection bridges
 * this: a well-known, write-ONCE **pointer** triple in the store-root names a
 * **doc-shim** (`did:ng:o:...`) that holds all account records and IS
 * subscribable. Resolution reads the pointer (a single oldest write-once triple,
 * near-always synced), then opens the doc-shim through its `ensureRepoOpen`
 * BARRIER and reads the account AUTHORITATIVELY (0 = genuinely absent).
 *
 * A pointer FORK (two devices writing the pointer before either synced) is
 * reconciled to a canonical doc-shim (lexicographically-smallest NURI) so every
 * device converges on the SAME doc-shim. This is why the OLD account-level retry
 * (`resolveAccountReliably` / `provisionRetry`) is GONE: the account read is now
 * barrier-authoritative, so it never needs to be retried to distinguish sync-lag
 * from absence. A micro-guard remains ONLY on the pointer read (one write-once
 * triple) — see resolvePointer.
 *
 * ── Generic by construction ──────────────────────────────────────────────
 * This module knows only the three native scopes; it knows no application
 * entity kind. The consumer maps its entities to a scope and calls
 * `createEntityDoc(scope)` / `listEntityDocs(scope)` with the resulting native
 * scope. No application domain here.
 *
 * ── What disappears at migration ─────────────────────────────────────────
 * At the real multi-store migration the shim vanishes entirely: `(account,
 * scope)` maps to the user's REAL store NURI instead of a document in the
 * shared wallet, `docCreate` targets the real per-user store, and the
 * per-scope index document (the store-container emulation) is replaced by the
 * store itself. The consumer-facing surface (`createEntityDoc`,
 * `listEntityDocs`, resolvers) is designed to survive that swap unchanged.
 *
 * All NextGraph I/O routes through the T01.a `docs` primitive (real injected
 * `ng`), so this module imports **no** `@ng-org` package.
 */

import { docCreate, sparqlUpdate, sparqlQuery } from "./docs";
import { getStoreRegistryDeps } from "./polyfill";
import { ensureRepoOpen } from "./open-repo";
import { escapeLiteral, escapeIri, assertNuri } from "./sparql";
import { accessLogPrefix, logStage, shortNuri } from "./access-log";
import type { Nuri, Scope } from "./types";

// --- sharedWalletShim model ----------------------------------------------

/** One account's three scope-document NURIs, as recorded in the shim. */
export interface AccountRecord {
  id: string;
  docPublic: Nuri;
  docProtected: Nuri;
  docPrivate: Nuri;
}

const SHIM = "urn:ng-eventually:shim";
const P = {
  type: `${SHIM}:Account`,
  id: `${SHIM}:id`,
  docPublic: `${SHIM}:docPublic`,
  docProtected: `${SHIM}:docProtected`,
  docPrivate: `${SHIM}:docPrivate`,
  contains: `${SHIM}:contains`, // scope-index → entity document NURI
} as const;
// Fixed subject of the per-(account×scope) index document. The index doc plays
// the role of the future store-container: it lists the NURIs of the entity
// documents (one per entity) that live "in" that scope.
const INDEX_SUBJECT = `${SHIM}:index`;

// --- pointer (store-root → doc-shim indirection) --------------------------
//
// The pointer is a SINGLE well-known triple written ONCE into the store-root
// graph on the very first login, then IMMUTABLE. Its object is the NURI of the
// doc-shim (a `did:ng:o:...` repo) where all AccountRecords actually live. The
// store-root is NOT subscribable (no first-`State` barrier), but the pointer is
// the OLDEST triple in that graph and is write-once, so it is near-always synced
// on a cold read — and even a transient miss is bounded by a small guard
// (resolvePointer), NOT by an account-level retry.
const POINTER_SUBJECT = `${SHIM}:root`;
const POINTER_PRED = `${SHIM}:shimDoc`;

function accountSubject(id: string): string {
  // The id is UNTRUSTED and lands in an IRI position. Percent-encode it
  // (escapeIri) so no `>` / `"` / whitespace / control char can break out of
  // the `<...>` and inject triples into the shim graph (the account→doc trust
  // root). accountKey() runs first so the subject stays stable per shim key.
  return `${SHIM}:account:${escapeIri(accountKey(id))}`;
}

// --- reserved accounts -----------------------------------------------------
//
// Some accounts are internal to the lib (e.g. the discovery index owner) and
// must NOT collide with any user-chosen id. A reserved account is created
// via {@link reservedAccount}, which marks the name with a sentinel PREFIX that
// `normalizeId` (consumer-injected) can never produce: it strips a leading
// `@`, trims, and lowercases, so a NUL prefix is unreachable. Reserved
// keys therefore live in a disjoint namespace from every normalized id —
// a real user named "index"/"@index" can never resolve to the reserved
// `reservedAccount("index")` account.
const RESERVED_PREFIX = "\u0000reserved:";

/**
 * Wrap an internal account name so it occupies a key that no user input can
 * produce (see {@link RESERVED_PREFIX}). Pass the result to {@link ensureAccount}
 * (and the other registry calls) instead of a bare id.
 */
export function reservedAccount(name: string): string {
  return `${RESERVED_PREFIX}${name}`;
}

/** Whether a name is a reserved-account sentinel (from {@link reservedAccount}). */
function isReserved(id: string): boolean {
  return id.startsWith(RESERVED_PREFIX);
}

/**
 * The shim/cache key for an account. Reserved accounts bypass `normalizeId`
 * entirely and key on their sentinel-prefixed name, so they cannot collide with
 * a normalized id; everyone else normalizes as usual.
 */
function accountKey(id: string): string {
  return isReserved(id) ? id : normalize(id);
}

// --- session / normalization access (injected by the consumer) ------------

/** Minimal session shape the registry needs — provided by the consumer. */
export interface RegistrySession {
  sessionId: string;
  /** The shared wallet's private store id — the pointer anchor. */
  privateStoreId: string;
  /** The shared wallet's protected store id (native store). Optional: only the
   *  scope resolvers need it; the shim only needs the private anchor. */
  protectedStoreId?: string;
  /** The shared wallet's public store id (native store). Optional. */
  publicStoreId?: string;
}

function normalize(id: string): string {
  return getStoreRegistryDeps().normalizeId(id);
}

async function session(): Promise<RegistrySession> {
  return getStoreRegistryDeps().getSession();
}

/** The pointer lives in the shared wallet's private STORE-ROOT graph (the only
 *  always-known-without-lookup anchor). NOT subscribable — hence the pointer is
 *  a write-once triple, and the actual account records live in the doc-shim it
 *  names (see rootNuri vs the doc-shim). */
async function rootNuri(): Promise<Nuri> {
  const s = await session();
  return `did:ng:${s.privateStoreId}`;
}

// --- cache ----------------------------------------------------------------

// In-memory cache of the FULL shim (all accounts), keyed by account key. Set
// only once loadShim() has read every account — used by the all-accounts paths.
let cache: Map<string, AccountRecord> | null = null;

// Per-account cache, keyed by account key. Populated by the TARGETED resolver
// (resolveAccount) and by loadShim(). Independent of `cache` so a single
// targeted resolve never forces a full shim scan. Both are cleared together.
const accountCache = new Map<string, AccountRecord>();

// The resolved doc-shim NURI for the current session (cached: the pointer read +
// barrier open happen once, then every account read reuses this doc). Cleared on
// resetRegistryCache / wallet switch.
let shimDocNuri: Nuri | null = null;
// De-dupe concurrent pointer-resolutions so a fresh page firing many parallel
// ensureAccount/resolveAccount calls opens the doc-shim exactly once.
let shimDocInFlight: Promise<Nuri> | null = null;

/** Reset cache (e.g. after switching the shared wallet). Mostly for tests. */
export function resetRegistryCache(): void {
  cache = null;
  accountCache.clear();
  shimDocNuri = null;
  shimDocInFlight = null;
}

// --- SPARQL result helpers ------------------------------------------------

/** Tolerant extraction of SPARQL SELECT bindings across possible shapes. */
function readBindings(result: unknown): Array<Record<string, { value: string }>> {
  if (!result) return [];
  const anyRes = result as {
    results?: { bindings?: Array<Record<string, { value: string }>> };
  };
  if (Array.isArray(result)) return result as Array<Record<string, { value: string }>>;
  if (anyRes.results?.bindings) return anyRes.results.bindings;
  return [];
}

function bindingValue(row: Record<string, { value: string }>, key: string): string {
  return row[key]?.value ?? "";
}

/**
 * DETERMINISTIC resolution of an account's scope docs from a set of SPARQL
 * bindings (all bindings for ONE account subject).
 *
 * ── Why this is load-bearing (residual fork residue) ───────────────────────
 * A corrupted shim can carry the SAME account subject with MULTIPLE values for a
 * scope predicate (e.g. 5 `shim:docPublic`) — the residue of past account FORKS
 * (each stray provision appended another doc NURI). A query then returns several
 * bindings (the cross-product of the duplicate values). Picking `rows[0]` is
 * NON-DETERMINISTIC (binding order is not stable across sessions), so the session
 * that WROTE an entity into one docPublic and a later fresh page that RESOLVED a
 * DIFFERENT docPublic would disagree → the anchored `readScopeIndex` returns 0 →
 * the home reads empty. When both happen to pick the same doc, it "works".
 *
 * The fix: for each scope field, collect EVERY distinct value across the bindings
 * and choose the SAME one every time — the lexicographically-smallest NURI. NURIs
 * are content-addressed and stable, so lexicographic order is a total, stable,
 * session-independent order: writer and reader converge on the SAME canonical doc
 * even on a wallet already corrupted by duplicates. (No creation timestamp is
 * recorded in the shim, so lexicographic-min is the available deterministic key.)
 *
 * With the barrier-authoritative doc-shim read, account FORKS no longer occur (a
 * fresh page reads the doc-shim through its first-`State` barrier, so a cold 0 is
 * definitive and never triggers a fork-provision). `canonicalDoc` is RETAINED to
 * stay robust against the residue of PAST forks already persisted in a wallet, and
 * to reconcile a benign pointer fork the same content-addressed way.
 */
function canonicalDoc(rows: Array<Record<string, { value: string }>>, key: string): Nuri {
  let chosen = "";
  const distinct = new Set<string>();
  for (const row of rows) {
    const v = bindingValue(row, key);
    if (!v) continue;
    distinct.add(v);
    if (chosen === "" || v < chosen) chosen = v;
  }
  // Stage trace: which doc got picked, and out of how many DISTINCT candidate
  // values — >1 flags residual fork residue (see the module doc above) even
  // when resolution still converges correctly on the canonical (smallest) one.
  logStage(
    "canonicalDoc(" + key + ") → " + (chosen ? shortNuri(chosen) : "none") +
      " (" + distinct.size + (distinct.size === 1 ? " candidate)" : " candidates)"),
  );
  return chosen;
}

/** Build an AccountRecord by picking the canonical (lexicographically-smallest)
 *  doc NURI per scope across all bindings for one account. See {@link canonicalDoc}. */
function recordFromRows(
  rows: Array<Record<string, { value: string }>>,
  fallbackId: string,
): AccountRecord {
  let id = "";
  for (const row of rows) {
    const v = bindingValue(row, "id");
    if (v) { id = v; break; }
  }
  return {
    id: id || fallbackId,
    docPublic: canonicalDoc(rows, "docPublic"),
    docProtected: canonicalDoc(rows, "docProtected"),
    docPrivate: canonicalDoc(rows, "docPrivate"),
  };
}

// --- pointer resolution + doc-shim bootstrap ------------------------------

const sleep = (ms: number): Promise<void> => new Promise((r) => setTimeout(r, ms));

/**
 * Read the pointer(s) from the store-root graph → the canonical doc-shim NURI, or
 * `""` if no pointer exists yet.
 *
 * The store-root is NOT subscribable, so this read has no first-`State` barrier:
 * a cold 0 is ambiguous. But the pointer is ONE write-once triple (the OLDEST in
 * that graph), so it is near-always synced. The ONLY residual guard is a small
 * bounded re-read here (NOT an account retry): a handful of quick re-reads of that
 * single triple. It is bounded, benign, and — crucially — it can never re-provision
 * an account or fork data; the worst it can do is take a couple extra reads to see a
 * pointer that is still landing. The account records themselves are read
 * authoritatively through the doc-shim barrier, never through this guard.
 *
 * If MULTIPLE pointers exist (a pointer fork: two devices each wrote a pointer to
 * their own freshly-created doc-shim before either synced), reconcile to the
 * canonical (lexicographically-smallest) doc-shim NURI — content-addressed and
 * stable, so every device converges on the SAME doc-shim.
 */
async function resolvePointer(): Promise<Nuri> {
  const s = await session();
  const root = await rootNuri();
  // COLD-START heal: open the store-root repo before the anchored read, so a fresh
  // wallet whose store-root isn't yet in `self.repos` resolves instead of throwing
  // `RepoNotFound`. Idempotent; a no-op with the unit fake ng. The store-root has no
  // barrier, so this open cannot make the read authoritative — the guard below does.
  await ensureRepoOpen(root);
  const query = `
    SELECT ?shimDoc WHERE {
      GRAPH <${assertNuri(root)}> {
        <${POINTER_SUBJECT}> <${POINTER_PRED}> ?shimDoc .
      }
    }`;

  // Micro-guard (POINTER only): a small bounded re-read to bridge the store-root
  // sync-lag window on the ONE write-once pointer triple. Bounded, and it can only
  // ever DELAY seeing an existing pointer — never provision, never fork. Uses the
  // injected pointerGuard budget (defaults to a single read when unset, so unit
  // fakes stay synchronous). NB this is NOT the deleted account-level provisionRetry.
  const budget = getStoreRegistryDeps().pointerGuard;
  const attempts = Math.max(1, budget.attempts ?? 1);
  const baseMs = budget.baseMs ?? 150;
  const maxStepMs = budget.maxStepMs ?? 2000;

  let step = baseMs;
  for (let i = 0; i < attempts; i++) {
    try {
      const result = await sparqlQuery(s.sessionId, query, undefined, root, "resolvePointer");
      const doc = canonicalDoc(readBindings(result), "shimDoc");
      if (doc) {
        logStage("resolvePointer → 1 target: " + shortNuri(doc));
        return doc;
      }
    } catch (error) {
      console.error(accessLogPrefix() + " resolvePointer failed:", error);
    }
    if (i < attempts - 1) {
      await sleep(step);
      step = Math.min(step * 2, maxStepMs);
    }
  }
  logStage("resolvePointer → 0 targets");
  return "";
}

/** Write the pointer (store-root → doc-shim), once, at first login. Idempotent in
 *  practice (only called when no pointer was found); a concurrent double-write is
 *  reconciled by canonicalDoc on read. */
async function writePointer(doc: Nuri): Promise<void> {
  const s = await session();
  const root = await rootNuri();
  await ensureRepoOpen(root);
  const update = `
    INSERT DATA {
      GRAPH <${assertNuri(root)}> {
        <${POINTER_SUBJECT}> <${POINTER_PRED}> <${assertNuri(doc)}> .
      }
    }`;
  try {
    await sparqlUpdate(s.sessionId, update, root, "writePointer");
  } catch (error) {
    console.error(accessLogPrefix() + " writePointer failed:", error);
  }
}

/** Create one graph document in the shared wallet's private store (→ a NURI). */
async function createDoc(): Promise<Nuri> {
  const s = await session();
  // crdt="Graph" (RDF/SPARQL/ORM), class="data:graph", destination="store",
  // store_repo=undefined → shared wallet's private store.
  return docCreate(s.sessionId, "Graph", "data:graph", "store", undefined);
}

/**
 * Resolve (or on first login, create) the doc-shim NURI for this session — the
 * `did:ng:o:...` repo that holds every AccountRecord and IS subscribable.
 *
 * Steps (cached; runs at most once per session, concurrent callers share one):
 *   1. Read the pointer from the store-root (resolvePointer). If present → that is
 *      the doc-shim; open it through its first-`State` BARRIER so subsequent account
 *      reads are AUTHORITATIVE.
 *   2. No pointer → FIRST login:
 *        a. create a fresh doc-shim (`doc_create`), which bootstraps the repo into the
 *           session (`self.repos`) — so it is already open/synced in-session;
 *        b. publish the pointer (store-root → the new doc-shim), once;
 *        c. open it (barrier — trivially satisfied for a just-created in-session repo).
 *      The BARRIER matters on RECONNECT (step 1, reading an EXISTING remote doc-shim);
 *      on first-login creation it is a no-op, so the pointer is published first.
 */
async function resolveShimDoc(): Promise<Nuri> {
  if (shimDocNuri) return shimDocNuri;
  if (shimDocInFlight) return shimDocInFlight;

  const p = (async (): Promise<Nuri> => {
    const existing = await resolvePointer();
    if (existing) {
      // Open the doc-shim through its first-`State` barrier BEFORE any account read,
      // so a cold 0 on the doc-shim is authoritative (genuinely absent), not sync-lag.
      await ensureRepoOpen(existing);
      shimDocNuri = existing;
      logStage("resolveShimDoc → " + shortNuri(existing));
      return existing;
    }

    // FIRST login (no pointer): create the doc-shim (bootstrapped in-session), publish
    // the pointer, then open (no-op barrier for a just-created repo).
    const doc = await createDoc();
    await writePointer(doc);
    await ensureRepoOpen(doc);
    shimDocNuri = doc;
    logStage("resolveShimDoc → " + shortNuri(doc));
    return doc;
  })();

  shimDocInFlight = p;
  try {
    return await p;
  } finally {
    shimDocInFlight = null;
  }
}

// --- shim load / account bootstrap ----------------------------------------

/** Load all accounts from the shim (the doc-shim) into the cache. */
export async function loadShim(): Promise<Map<string, AccountRecord>> {
  if (cache) return cache;
  const s = await session();
  const doc = await resolveShimDoc();
  const query = `
    SELECT ?id ?docPublic ?docProtected ?docPrivate WHERE {
      ?acc a <${P.type}> ;
           <${P.id}> ?id ;
           <${P.docPublic}> ?docPublic ;
           <${P.docProtected}> ?docProtected ;
           <${P.docPrivate}> ?docPrivate .
    }`;
  const map = new Map<string, AccountRecord>();
  // The doc-shim is opened (first-`State` barrier) by resolveShimDoc, so this read is
  // authoritative.
  await ensureRepoOpen(doc);
  try {
    const result = await sparqlQuery(s.sessionId, query, undefined, doc, "loadShim");
    // Group ALL bindings by account key first, then pick the CANONICAL doc per
    // scope (see recordFromRows / canonicalDoc). A single account subject may carry
    // duplicate scope-doc values (fork residue) → several bindings; grouping +
    // canonical selection makes loadShim resolve the SAME doc the targeted
    // resolveAccount does, so full-scan and hot-path readers never disagree.
    const byKey = new Map<string, Array<Record<string, { value: string }>>>();
    for (const row of readBindings(result)) {
      const id = bindingValue(row, "id");
      if (!id) continue;
      const key = accountKey(id);
      const bucket = byKey.get(key) ?? [];
      bucket.push(row);
      byKey.set(key, bucket);
    }
    for (const [key, rows] of byKey) {
      const record = recordFromRows(rows, rows[0] ? bindingValue(rows[0], "id") : key);
      map.set(key, record);
      // Feed the per-account cache too, so a subsequent targeted resolve is free.
      accountCache.set(key, record);
    }
  } catch (error) {
    console.error(accessLogPrefix() + " loadShim failed:", error);
  }
  cache = map;
  return map;
}

/**
 * Resolve ONE account by its shim key with a BOUNDED query — O(1), independent
 * of the number of accounts in the shim. This is the HOT-PATH lookup: it hits
 * the account record at its known subject (`accountSubject(id)`) directly in the
 * doc-shim, instead of scanning EVERY account like {@link loadShim}. Returns the
 * account's record or `null` if it does not exist yet.
 *
 * ── Barrier-AUTHORITATIVE (the reconnection fix) ────────────────────────────
 * The read targets the DOC-SHIM (`did:ng:o:...`), which resolveShimDoc opened
 * through its first-`State` barrier. So a cold 0 rows here is DEFINITIVE ("account
 * genuinely absent"), not ambiguous sync-lag — no account-level retry is needed or
 * used. This is what replaced the old `resolveAccountReliably` / `provisionRetry`
 * loop: the store-root ambiguity that forced the retry is gone once the read moves
 * behind the doc-shim barrier.
 *
 * Cached per account (in `accountCache`); a hit skips the query entirely, so
 * repeated resolves of the same account are free. `resetRegistryCache` clears it.
 */
export async function resolveAccount(id: string): Promise<AccountRecord | null> {
  const key = accountKey(id);
  const cached = accountCache.get(key);
  if (cached) return cached;

  const s = await session();
  const doc = await resolveShimDoc();
  // `subj` is already IRI-safe (accountSubject → escapeIri). The read is anchored to
  // the doc-shim's default graph (opened through its barrier by resolveShimDoc), so
  // it is authoritative. The query is bounded to this one subject.
  const subj = accountSubject(id);
  const query = `
    SELECT ?id ?docPublic ?docProtected ?docPrivate WHERE {
      <${subj}> a <${P.type}> ;
           <${P.id}> ?id ;
           <${P.docPublic}> ?docPublic ;
           <${P.docProtected}> ?docProtected ;
           <${P.docPrivate}> ?docPrivate .
    }`;
  try {
    const result = await sparqlQuery(s.sessionId, query, undefined, doc, "resolveAccount");
    const rows = readBindings(result);
    if (rows.length === 0) {
      logStage("resolveAccount(" + key + ") → null");
      return null;
    }
    // DETERMINISTIC: a corrupted shim may return SEVERAL bindings for this one
    // account subject (duplicate scope-doc values from past forks). Pick the
    // canonical (lexicographically-smallest) doc per scope so writer and reader
    // always resolve the SAME docPublic (robustness against PAST fork residue).
    const record = recordFromRows(rows, id);
    accountCache.set(key, record);
    logStage("resolveAccount(" + key + ") → 1 record");
    return record;
  } catch (error) {
    console.error(accessLogPrefix() + " resolveAccount failed:", error);
    return null;
  }
}

/** All known accounts (from the shim). */
export async function allAccounts(): Promise<AccountRecord[]> {
  return [...(await loadShim()).values()];
}

/** Persist one AccountRecord into the doc-shim (anchored default-graph write, the
 *  canonical always-safe shape — same convention as createEntityDoc). */
async function writeRecord(doc: Nuri, record: AccountRecord): Promise<void> {
  const s = await session();
  const subj = `${SHIM}:account:${escapeIri(accountKey(record.id))}`;
  // `subj` is IRI-safe (escapeIri). `id` is UNTRUSTED text in a LITERAL position →
  // escapeLiteral. The doc NURIs come from `ng` but are stored as literals here, so
  // they are escaped as literals too (defence in depth). NO explicit `GRAPH <…>`
  // wrapper: write the anchored DEFAULT graph (the `doc` anchor scopes it) — the
  // canonical, always-safe shape the anchored default-graph read queries match.
  const update = `
    INSERT DATA {
      <${subj}> a <${P.type}> ;
        <${P.id}> "${escapeLiteral(record.id)}" ;
        <${P.docPublic}> "${escapeLiteral(record.docPublic)}" ;
        <${P.docProtected}> "${escapeLiteral(record.docProtected)}" ;
        <${P.docPrivate}> "${escapeLiteral(record.docPrivate)}" .
    }`;
  try {
    await sparqlUpdate(s.sessionId, update, doc, "writeRecord");
  } catch (error) {
    console.error(accessLogPrefix() + " writeRecord persist failed:", error);
  }
}

/**
 * In-flight `ensureAccount` promises, keyed by account key — so CONCURRENT
 * `ensureAccount(id)` calls for the SAME account share ONE resolve-or-provision.
 *
 * ── Why this is load-bearing (concurrent-provision de-dup) ──────────────────
 * On a fresh page over the persistent wallet, SEVERAL independent callers hit
 * `ensureAccount(A)` near-simultaneously (watchShape public/protected, the container
 * subscriptions, the app's owned-events effect). With the barrier-authoritative
 * resolveAccount a fresh page NO LONGER mistakes sync-lag for absence — but if the
 * account is GENUINELY new, N concurrent callers would still each see 0 and each
 * provision a set of scope docs (an in-session fork). De-duping concurrent provisions
 * collapses those N into ONE: the first caller resolves-or-provisions; every
 * concurrent caller awaits the SAME promise and gets the SAME record. Not polling: a
 * bounded in-memory promise map (mirrors open-repo.ts `inFlight`), cleared the instant
 * it settles.
 */
const ensureInFlight = new Map<string, Promise<AccountRecord>>();

/**
 * Ensure an account exists in the shim, creating its 3 scope documents on
 * first sight. Idempotent — returns the existing record if already present.
 * Concurrency-safe: concurrent calls for the same account share one provision
 * (see {@link ensureInFlight}) so a fresh page never FORKS the account.
 */
export async function ensureAccount(id: string): Promise<AccountRecord> {
  const key = accountKey(id);
  // A completed provision/resolve is cached → no query, no fork risk.
  const cached = accountCache.get(key);
  if (cached) return cached;
  // A concurrent provision for the SAME account is already running → await it,
  // instead of racing a second (forking) provision. This is the anti-fork guard.
  const pending = ensureInFlight.get(key);
  if (pending) return pending;

  const p = (async (): Promise<AccountRecord> => {
    // HOT PATH: targeted O(1) lookup — does THIS account already exist? — instead
    // of a full-shim scan (loadShim). Off the read/write hot path entirely.
    //
    // Barrier-AUTHORITATIVE: resolveAccount reads the doc-shim behind its first-`State`
    // barrier (opened by resolveShimDoc), so a 0 here means the account is GENUINELY
    // absent — not sync-lag. No account-level retry: the store-root ambiguity that
    // forced the old provisionRetry loop is gone once the read moves behind the barrier.
    const existing = await resolveAccount(id);
    if (existing) return existing;

    const doc = await resolveShimDoc();
    const [docPublic, docProtected, docPrivate] = await Promise.all([
      createDoc(),
      createDoc(),
      createDoc(),
    ]);
    const record: AccountRecord = { id, docPublic, docProtected, docPrivate };
    // Persist the record INTO the doc-shim (not the store-root anymore).
    await writeRecord(doc, record);
    // Feed the per-account cache, and the full-shim cache if it is already loaded
    // (so allAccounts / the fan-out see the freshly-created account too).
    accountCache.set(key, record);
    cache?.set(key, record);
    return record;
  })();

  ensureInFlight.set(key, p);
  try {
    return await p;
  } finally {
    ensureInFlight.delete(key);
  }
}

// --- resolvers ------------------------------------------------------------

/** The index document NURI of an account for a scope (the store-container). */
function indexDocOf(record: AccountRecord, scope: Scope): Nuri {
  return scope === "public"
    ? record.docPublic
    : scope === "protected"
    ? record.docProtected
    : record.docPrivate;
}

/**
 * NURI of the document where `id` writes GROUPED entities of `scope` (a single
 * per-scope index document, for entities that need no per-entity document / no
 * inbox). For per-entity scopes use {@link createEntityDoc} instead.
 */
export async function resolveWriteGraph(id: string, scope: Scope): Promise<Nuri> {
  const record = await ensureAccount(id);
  return indexDocOf(record, scope);
}

/** NURIs of every account's document for `scope` (read fan-out). */
export async function resolveReadGraphs(scope: Scope): Promise<Nuri[]> {
  const accounts = await allAccounts();
  return accounts.map((a) => indexDocOf(a, scope));
}

// --- SDK-shaped scope resolvers (no store-id ever leaves the lib) ----------
//
// The consumer asks by SCOPE ("give me the graph to write/read entities of
// scope X", "give me the inbox anchor") and NEVER constructs a `did:ng:${…}`
// store NURI itself. The lib owns the physical placement — which is the whole
// point of the SDK boundary. In THIS polyfill the placement is the shared
// wallet's native stores (Axis A, per the two-axes doctrine in
// docs/simulation.md): a scope maps to a native store NURI resolved from the
// injected session. `public` currently co-locates with `protected` because
// `doc_create`/ORM cannot target a non-private/protected native store today
// (the SDK blocker recorded in migration-guide.md); at migration each scope
// resolves to the user's REAL per-scope store and this mapping changes here,
// in the lib, with no consumer change.

/** The native store NURI backing `scope`, resolved from the injected session.
 *  Requires `protectedStoreId` on the session for the non-private scopes. */
async function scopeStoreNuri(scope: Scope): Promise<Nuri> {
  const s = await session();
  if (scope === "private") return `did:ng:${s.privateStoreId}`;
  // public + protected → the protected native store (see note above). Falls
  // back to the private store if the session didn't carry a protected id.
  const store = s.protectedStoreId ?? s.privateStoreId;
  return `did:ng:${store}`;
}

/**
 * The graph NURI where the current session WRITES entities of `scope`, and
 * whose repo `useShape` must subscribe to read them back. SDK-shaped: the
 * consumer passes a logical scope and gets an opaque graph NURI — it holds no
 * store-id and builds no NURI. Use the returned value as both the read scope
 * (`useShape(shape, nuri)`) and the `@graph` write target.
 */
export async function resolveScopeGraph(scope: Scope): Promise<Nuri> {
  return scopeStoreNuri(scope);
}

/**
 * The reserved account that OWNS the shared registration-inbox document. Like the
 * discovery index's special account, it lives in the reserved namespace (no user
 * can produce this key) and only HOSTS a document — its `public` scope document is
 * the inbox anchor. Disappears at migration (native per-document inboxes).
 */
const INBOX_ANCHOR_ACCOUNT = reservedAccount("inbox");

/**
 * The inbox anchor NURI for the current session (where emulated inbox deposits
 * physically land). SDK-shaped: the consumer never resolves a store itself.
 *
 * This is a DEDICATED inbox DOCUMENT (a reserved account's public scope document —
 * a real repo NURI from `docCreate`, stable across clients via the shim), NOT the
 * shared wallet's private-store root. Reason (perf + hygiene): the shim (the
 * account→document trust root) is scanned on every `loadShim`; routing every inbox
 * deposit into that SAME graph bloats it without bound (thousands of deposit triples
 * across sessions). A separate inbox document keeps the shim graph small and the
 * deposits isolated. At migration this becomes the host's native per-document inbox
 * and the resolution moves here.
 */
export async function resolveInboxAnchor(): Promise<Nuri> {
  const record = await ensureAccount(INBOX_ANCHOR_ACCOUNT);
  return record.docPublic;
}

// --- per-entity documents + per-scope index -------------------------------

/**
 * Create a dedicated document for ONE entity — mirrors the target, where each
 * such entity is its own document/repo (addressable, future inbox). The new
 * document's NURI is appended to the account's scope index document (the
 * store-container). Returns the entity document NURI (use it as `@graph`).
 */
export async function createEntityDoc(id: string, scope: Scope): Promise<Nuri> {
  const record = await ensureAccount(id);
  const indexDoc = indexDocOf(record, scope);
  const entityNuri = await createDoc();
  const s = await session();
  try {
    await sparqlUpdate(
      s.sessionId,
      // NO explicit `GRAPH <…>` wrapper: write the anchored DEFAULT graph (the
      // `indexDoc` anchor scopes it) — the CANONICAL, always-safe shape the
      // anchored default-graph read queries (readScopeIndex below, same as
      // read-model.ts). Not a round-trip necessity on the current broker: the e2e
      // harness (`packages/client/e2e/`) verified an anchored `GRAPH <plainNuri>`
      // write ALSO round-trips here (same repo graph, no phantom graph); no-GRAPH
      // is kept as a simplicity/safety convention. entityNuri is a NURI stored as
      // a literal → escapeLiteral.
      `INSERT DATA { <${INDEX_SUBJECT}> <${P.contains}> "${escapeLiteral(entityNuri)}" }`,
      indexDoc,
      "createEntityDoc",
    );
  } catch (error) {
    console.error(accessLogPrefix() + " createEntityDoc index append failed:", error);
  }
  return entityNuri;
}

/** Read the entity-document NURIs contained in ONE scope index document. */
async function readScopeIndex(indexDoc: Nuri): Promise<Nuri[]> {
  const s = await session();
  const out: Nuri[] = [];
  // COLD-START heal (polyfill-era): on a fresh session over a persistent wallet the
  // scope-index repo (public OR protected — the protected one carries participations
  // and is the one that most often reads empty) is not yet in `self.repos`, so this
  // anchored read would return 0 NURIs → nothing gets listed → nothing gets
  // subscribed (the self-inflicted circularity). Open/subscribe the index repo ONCE
  // before reading it. Idempotent per session; no-op with the unit fake ng. See
  // open-repo.ts.
  await ensureRepoOpen(indexDoc);
  try {
    const res = await sparqlQuery(
      s.sessionId,
      // NO explicit `GRAPH <…>` clause — read the anchored DEFAULT graph (see
      // the note in createEntityDoc). The `indexDoc` anchor scopes the query.
      `SELECT ?e WHERE { <${INDEX_SUBJECT}> <${P.contains}> ?e }`,
      undefined,
      indexDoc,
      "readScopeIndex",
    );
    for (const row of readBindings(res)) {
      const v = bindingValue(row, "e");
      if (v) out.push(v);
    }
  } catch (error) {
    console.error(accessLogPrefix() + " readScopeIndex failed:", error);
  }
  logStage("readScopeIndex(" + shortNuri(indexDoc) + ") → " + out.length + " entities");
  return out;
}

/**
 * Every entity document NURI of `scope`, across all accounts — the read
 * fan-out for per-entity scopes. Reads each account's scope index document and
 * unions the contained NURIs. Use as `useShape(shape, { graphs })`.
 *
 * NOTE (read-by-need): this ALL-ACCOUNTS fan-out contradicts the read-by-need
 * model (docs/read-model.md) — it opens/syncs other accounts' possibly-unsynced
 * docs, which HANGS. Prefer {@link listMyEntityDocs} (my own account's scope
 * docs) for "my entities", and the discovery index for "all public events".
 * Retained for callers that legitimately need every account (tests).
 */
export async function listEntityDocs(scope: Scope): Promise<Nuri[]> {
  const accounts = await allAccounts();
  const out: Nuri[] = [];
  for (const a of accounts) {
    out.push(...(await readScopeIndex(indexDocOf(a, scope))));
  }
  return out;
}

/**
 * The scope-INDEX document NURI of ONE account (`id`) for `scope` — the
 * store-container document that LISTS the account's per-entity document NURIs
 * (what {@link listMyEntityDocs} reads). Exposed so a reactive reader
 * ({@link watchShape}) can SUBSCRIBE to this index document and re-resolve the
 * entity-doc set when the index changes (a new entity created appends a NURI
 * here). Idempotent via `ensureAccount`'s cache. At migration this becomes the
 * user's real per-scope store NURI (the container the store itself provides).
 */
export async function scopeIndexDoc(id: string, scope: Scope): Promise<Nuri> {
  const record = await ensureAccount(id);
  return indexDocOf(record, scope);
}

/**
 * The entity-document NURIs of `scope` belonging to ONE account (`id`) —
 * the read-by-need path for one account's own entities. Bounded to a SINGLE
 * account: it resolves only that account's scope index doc (via `ensureAccount`)
 * and reads the contained NURIs — NO cross-account fan-out, so it never touches
 * another account's unsynced docs. This is the helper a consumer application uses
 * for its own my-entities path, instead of the all-accounts `listEntityDocs`.
 */
export async function listMyEntityDocs(id: string, scope: Scope): Promise<Nuri[]> {
  const record = await ensureAccount(id);
  return readScopeIndex(indexDocOf(record, scope));
}