diff --git a/packages/gittensory-miner/lib/event-ledger.d.ts b/packages/gittensory-miner/lib/event-ledger.d.ts
new file mode 100644
index 0000000000..480474a4e1
--- /dev/null
+++ b/packages/gittensory-miner/lib/event-ledger.d.ts
@@ -0,0 +1,36 @@
+export type LedgerEntry = {
+  id: number;
+  seq: number;
+  type: string;
+  repoFullName: string | null;
+  payload: Record<string, unknown>;
+  createdAt: string;
+};
+
+export type AppendEventInput = {
+  type: string;
+  repoFullName?: string;
+  payload: Record<string, unknown>;
+};
+
+export type ReadEventsFilter = {
+  repoFullName?: string;
+  since?: number;
+};
+
+export type EventLedger = {
+  dbPath: string;
+  appendEvent(event: AppendEventInput): LedgerEntry;
+  readEvents(filter?: ReadEventsFilter): LedgerEntry[];
+  close(): void;
+};
+
+export function resolveEventLedgerDbPath(env?: Record<string, string | undefined>): string;
+
+export function initEventLedger(dbPath?: string): EventLedger;
+
+export function appendEvent(event: AppendEventInput): LedgerEntry;
+
+export function readEvents(filter?: ReadEventsFilter): LedgerEntry[];
+
+export function closeDefaultEventLedger(): void;
diff --git a/packages/gittensory-miner/lib/event-ledger.js b/packages/gittensory-miner/lib/event-ledger.js
new file mode 100644
index 0000000000..116b09eaf3
--- /dev/null
+++ b/packages/gittensory-miner/lib/event-ledger.js
@@ -0,0 +1,195 @@
+import { chmodSync, mkdirSync } from "node:fs";
+import { homedir } from "node:os";
+import { dirname, join } from "node:path";
+import { DatabaseSync } from "node:sqlite";
+import { isDeepStrictEqual } from "node:util";
+
+// The miner's local, append-only event ledger (#2290): an immutable audit trail of every significant miner-loop
+// event (discovered_issue, plan_built, plan_step_completed, pr_prepared, … — a small fixed vocabulary for this
+// foundation phase that grows in later phases), each stamped with a module-maintained monotonic `seq` and a
+// timestamp. IMMUTABILITY INVARIANT: this module only ever issues INSERT and SELECT — it NEVER rewrites or removes
+// a row, so a contributor auditing the miner's history later can trust it was not retroactively edited. Keep it
+// that way: do not add any statement that mutates or removes an existing row. The database is 100% local; this
+// module never uploads, syncs, or phones home with its contents. Mirrors the local-store pattern of run-state.js.
+
+const defaultDbFileName = "event-ledger.sqlite3";
+let defaultEventLedger = null;
+
+export function resolveEventLedgerDbPath(env = process.env) {
+  const explicitPath = typeof env.GITTENSORY_MINER_EVENT_LEDGER_DB === "string"
+    ? env.GITTENSORY_MINER_EVENT_LEDGER_DB.trim()
+    : "";
+  if (explicitPath) return explicitPath;
+
+  const explicitConfigDir = typeof env.GITTENSORY_MINER_CONFIG_DIR === "string"
+    ? env.GITTENSORY_MINER_CONFIG_DIR.trim()
+    : "";
+  if (explicitConfigDir) return join(explicitConfigDir, defaultDbFileName);
+
+  const configHome = typeof env.XDG_CONFIG_HOME === "string" && env.XDG_CONFIG_HOME.trim()
+    ? env.XDG_CONFIG_HOME.trim()
+    : join(homedir(), ".config");
+  return join(configHome, "gittensory-miner", defaultDbFileName);
+}
+
+function normalizeDbPath(dbPath) {
+  const path = (dbPath ?? resolveEventLedgerDbPath()).trim();
+  if (!path) throw new Error("invalid_event_ledger_db_path");
+  return path;
+}
+
+function normalizeEventType(type) {
+  if (typeof type !== "string") throw new Error("invalid_event_type");
+  const trimmed = type.trim();
+  if (!trimmed) throw new Error("invalid_event_type");
+  return trimmed;
+}
+
+/** Optional repo scope: omitted/nullish → null; otherwise a validated `owner/repo`. */
+function normalizeOptionalRepoFullName(repoFullName) {
+  if (repoFullName === undefined || repoFullName === null) return null;
+  if (typeof repoFullName !== "string") throw new Error("invalid_repo_full_name");
+  const [owner, repo, extra] = repoFullName.trim().split("/");
+  if (!owner || !repo || extra !== undefined) throw new Error("invalid_repo_full_name");
+  return `${owner}/${repo}`;
+}
+
+// Serialize an audit payload, enforcing that it round-trips through JSON VERBATIM. A plain JSON.stringify would
+// silently drop `undefined`/function/symbol values and coerce `NaN`/`Infinity` to `null` (and throw on BigInt or a
+// cycle), so a read-back would not equal the appended event. We reject any such lossy payload outright — an audit
+// ledger must return exactly what was recorded.
+function serializePayload(payload) {
+  if (payload === null || typeof payload !== "object" || Array.isArray(payload)) {
+    throw new Error("invalid_payload");
+  }
+  let json;
+  try {
+    json = JSON.stringify(payload);
+  } catch {
+    throw new Error("invalid_payload"); // BigInt value or circular reference
+  }
+  if (!isDeepStrictEqual(JSON.parse(json), payload)) {
+    throw new Error("invalid_payload"); // a value JSON would drop or coerce (undefined/NaN/function/symbol/Date/…)
+  }
+  return json;
+}
+
+function rowToEntry(row) {
+  return {
+    id: row.id,
+    seq: row.seq,
+    type: row.event_type,
+    repoFullName: row.repo_full_name,
+    payload: JSON.parse(row.payload_json),
+    createdAt: row.created_at,
+  };
+}
+
+/**
+ * Opens the local append-only event ledger, creating the table on first use. `seq` is a monotonically increasing
+ * counter maintained by this module (next = current MAX(seq) + 1) rather than relying on `AUTOINCREMENT`'s
+ * reuse-after-vacuum behavior, so consumers get a stable ordering guarantee. Rows read back in `seq ASC` order.
+ * (#2290)
+ */
+export function initEventLedger(dbPath = resolveEventLedgerDbPath()) {
+  const resolvedPath = normalizeDbPath(dbPath);
+  mkdirSync(dirname(resolvedPath), { recursive: true, mode: 0o700 });
+  const db = new DatabaseSync(resolvedPath);
+  chmodSync(resolvedPath, 0o600);
+  // Wait (rather than fail) for a concurrent writer's lock so two ledger instances on the same file serialize.
+  db.exec("PRAGMA busy_timeout = 5000");
+  // `UNIQUE(seq)` makes the monotonic-ordering guarantee an enforced invariant: a duplicate seq can never persist,
+  // even if the append path were ever changed.
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS miner_event_ledger (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      seq INTEGER NOT NULL UNIQUE,
+      event_type TEXT NOT NULL,
+      repo_full_name TEXT,
+      payload_json TEXT NOT NULL,
+      created_at TEXT NOT NULL
+    )
+  `);
+
+  const nextSeqStatement = db.prepare("SELECT COALESCE(MAX(seq), 0) + 1 AS nextSeq FROM miner_event_ledger");
+  const appendStatement = db.prepare(`
+    INSERT INTO miner_event_ledger (seq, event_type, repo_full_name, payload_json, created_at)
+    VALUES (?, ?, ?, ?, ?)
+  `);
+  const getByIdStatement = db.prepare("SELECT * FROM miner_event_ledger WHERE id = ?");
+  const readAllStatement = db.prepare("SELECT * FROM miner_event_ledger ORDER BY seq ASC");
+  const readByRepoStatement = db.prepare(
+    "SELECT * FROM miner_event_ledger WHERE repo_full_name = ? ORDER BY seq ASC",
+  );
+  const readSinceStatement = db.prepare(
+    "SELECT * FROM miner_event_ledger WHERE seq > ? ORDER BY seq ASC",
+  );
+  const readByRepoSinceStatement = db.prepare(
+    "SELECT * FROM miner_event_ledger WHERE repo_full_name = ? AND seq > ? ORDER BY seq ASC",
+  );
+
+  return {
+    dbPath: resolvedPath,
+    appendEvent(event) {
+      const type = normalizeEventType(event?.type);
+      const repoFullName = normalizeOptionalRepoFullName(event?.repoFullName);
+      const payloadJson = serializePayload(event?.payload);
+      const createdAt = new Date().toISOString();
+      // Serialize the read-then-write: BEGIN IMMEDIATE takes the write lock BEFORE reading MAX(seq), so two ledger
+      // instances on the same file cannot both compute the same next seq and corrupt the ordering guarantee.
+      db.exec("BEGIN IMMEDIATE");
+      try {
+        const { nextSeq } = nextSeqStatement.get();
+        const result = appendStatement.run(nextSeq, type, repoFullName, payloadJson, createdAt);
+        const entry = rowToEntry(getByIdStatement.get(Number(result.lastInsertRowid)));
+        db.exec("COMMIT");
+        return entry;
+      } catch (error) {
+        db.exec("ROLLBACK");
+        throw error;
+      }
+    },
+    readEvents(filter = {}) {
+      const repoFullName = filter.repoFullName === undefined
+        ? undefined
+        : normalizeOptionalRepoFullName(filter.repoFullName);
+      // `since` returns events with a seq STRICTLY greater than it — the "give me everything after the last seq I
+      // saw" polling shape.
+      const since = typeof filter.since === "number" ? filter.since : undefined;
+
+      let rows;
+      if (repoFullName !== undefined && since !== undefined) {
+        rows = readByRepoSinceStatement.all(repoFullName, since);
+      } else if (repoFullName !== undefined) {
+        rows = readByRepoStatement.all(repoFullName);
+      } else if (since !== undefined) {
+        rows = readSinceStatement.all(since);
+      } else {
+        rows = readAllStatement.all();
+      }
+      return rows.map(rowToEntry);
+    },
+    close() {
+      db.close();
+    },
+  };
+}
+
+function getDefaultEventLedger() {
+  defaultEventLedger ??= initEventLedger();
+  return defaultEventLedger;
+}
+
+export function appendEvent(event) {
+  return getDefaultEventLedger().appendEvent(event);
+}
+
+export function readEvents(filter) {
+  return getDefaultEventLedger().readEvents(filter);
+}
+
+export function closeDefaultEventLedger() {
+  if (!defaultEventLedger) return;
+  defaultEventLedger.close();
+  defaultEventLedger = null;
+}
diff --git a/packages/gittensory-miner/package.json b/packages/gittensory-miner/package.json
index 32e000a94e..7e175d4c58 100644
--- a/packages/gittensory-miner/package.json
+++ b/packages/gittensory-miner/package.json
@@ -31,7 +31,7 @@
     "lib"
   ],
   "scripts": {
-    "build": "node --check bin/gittensory-miner.js && node --check lib/cli.js && node --check lib/deny-check.js && node --check lib/update-check.js && node --check lib/opportunity-fanout.js && node --check lib/ci-poller.js && node --check lib/run-state.js && node --check lib/deny-hooks.js"
+    "build": "node --check bin/gittensory-miner.js && node --check lib/cli.js && node --check lib/deny-check.js && node --check lib/update-check.js && node --check lib/opportunity-fanout.js && node --check lib/ci-poller.js && node --check lib/run-state.js && node --check lib/deny-hooks.js && node --check lib/event-ledger.js"
   },
   "dependencies": {
     "@jsonbored/gittensory-engine": "0.1.0"
diff --git a/test/unit/miner-event-ledger.test.ts b/test/unit/miner-event-ledger.test.ts
new file mode 100644
index 0000000000..ebaae1f7e8
--- /dev/null
+++ b/test/unit/miner-event-ledger.test.ts
@@ -0,0 +1,125 @@
+import { mkdtempSync, readFileSync, rmSync, statSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+import {
+  closeDefaultEventLedger,
+  initEventLedger,
+  resolveEventLedgerDbPath,
+} from "../../packages/gittensory-miner/lib/event-ledger.js";
+
+const roots: string[] = [];
+const ledgers: Array<{ close(): void }> = [];
+
+function tempLedger() {
+  const root = mkdtempSync(join(tmpdir(), "gittensory-miner-event-ledger-"));
+  roots.push(root);
+  const ledger = initEventLedger(join(root, "nested", "event-ledger.sqlite3"));
+  ledgers.push(ledger);
+  return ledger;
+}
+
+afterEach(() => {
+  for (const ledger of ledgers.splice(0)) ledger.close();
+  closeDefaultEventLedger();
+  for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true });
+});
+
+describe("gittensory-miner event ledger (#2290)", () => {
+  it("resolves the DB path from env override, miner config dir, XDG config, then the home default", () => {
+    expect(resolveEventLedgerDbPath({ GITTENSORY_MINER_EVENT_LEDGER_DB: "/custom/e.sqlite3" })).toBe(
+      "/custom/e.sqlite3",
+    );
+    expect(resolveEventLedgerDbPath({ GITTENSORY_MINER_CONFIG_DIR: "/custom/config" })).toBe(
+      "/custom/config/event-ledger.sqlite3",
+    );
+    expect(resolveEventLedgerDbPath({ XDG_CONFIG_HOME: "/xdg" })).toBe(
+      "/xdg/gittensory-miner/event-ledger.sqlite3",
+    );
+    expect(resolveEventLedgerDbPath({})).toMatch(/\/\.config\/gittensory-miner\/event-ledger\.sqlite3$/);
+  });
+
+  it("creates the SQLite file with owner-only permissions and reads empty before any append", () => {
+    const ledger = tempLedger();
+    expect(statSync(ledger.dbPath).mode & 0o077).toBe(0);
+    expect(ledger.readEvents()).toEqual([]);
+  });
+
+  it("appends an event and reads it back verbatim (JSON payload round-trip)", () => {
+    const ledger = tempLedger();
+    const entry = ledger.appendEvent({
+      type: "discovered_issue",
+      repoFullName: "JSONbored/gittensory",
+      payload: { issueNumber: 2290, labels: ["gittensor:feature"] },
+    });
+    expect(entry).toMatchObject({
+      seq: 1,
+      type: "discovered_issue",
+      repoFullName: "JSONbored/gittensory",
+      payload: { issueNumber: 2290, labels: ["gittensor:feature"] },
+    });
+    expect(typeof entry.id).toBe("number");
+    expect(typeof entry.createdAt).toBe("string");
+    expect(ledger.readEvents()).toEqual([entry]);
+  });
+
+  it("stores a null repo scope when none is given", () => {
+    const ledger = tempLedger();
+    expect(ledger.appendEvent({ type: "plan_built", payload: { steps: 3 } }).repoFullName).toBeNull();
+  });
+
+  it("assigns a strictly monotonic, gapless, unique seq across many appends", () => {
+    const ledger = tempLedger();
+    for (let i = 0; i < 50; i += 1) ledger.appendEvent({ type: "discovered_issue", payload: { i } });
+    const seqs = ledger.readEvents().map((entry) => entry.seq);
+    expect(seqs).toEqual(Array.from({ length: 50 }, (_unused, i) => i + 1)); // 1..50, gapless
+    expect(new Set(seqs).size).toBe(50); // all unique
+  });
+
+  it("filters by repoFullName", () => {
+    const ledger = tempLedger();
+    ledger.appendEvent({ type: "discovered_issue", repoFullName: "o/a", payload: {} });
+    ledger.appendEvent({ type: "discovered_issue", repoFullName: "o/b", payload: {} });
+    ledger.appendEvent({ type: "plan_built", repoFullName: "o/a", payload: {} });
+    expect(ledger.readEvents({ repoFullName: "o/a" }).map((entry) => entry.type)).toEqual([
+      "discovered_issue",
+      "plan_built",
+    ]);
+  });
+
+  it("filters by `since` (strictly greater seq), and combines with repoFullName", () => {
+    const ledger = tempLedger();
+    ledger.appendEvent({ type: "discovered_issue", repoFullName: "o/a", payload: {} }); // seq 1
+    ledger.appendEvent({ type: "plan_built", repoFullName: "o/b", payload: {} }); // seq 2
+    ledger.appendEvent({ type: "pr_prepared", repoFullName: "o/a", payload: {} }); // seq 3
+    expect(ledger.readEvents({ since: 1 }).map((entry) => entry.seq)).toEqual([2, 3]);
+    expect(ledger.readEvents({ repoFullName: "o/a", since: 1 }).map((entry) => entry.seq)).toEqual([3]);
+  });
+
+  it("rejects a non-object payload and a malformed repo scope rather than persisting them", () => {
+    const ledger = tempLedger();
+    // @ts-expect-error — payload must be an object
+    expect(() => ledger.appendEvent({ type: "x", payload: "nope" })).toThrow("invalid_payload");
+    expect(() => ledger.appendEvent({ type: "  ", payload: {} })).toThrow("invalid_event_type");
+    expect(() => ledger.appendEvent({ type: "x", repoFullName: "no-slash", payload: {} })).toThrow(
+      "invalid_repo_full_name",
+    );
+  });
+
+  it("rejects a payload JSON would not round-trip verbatim, and accepts a nested JSON-safe one", () => {
+    const ledger = tempLedger();
+    // Values JSON drops or coerces would make the audit entry differ from what was appended.
+    expect(() => ledger.appendEvent({ type: "x", payload: { a: undefined } })).toThrow("invalid_payload");
+    expect(() => ledger.appendEvent({ type: "x", payload: { a: Number.NaN } })).toThrow("invalid_payload");
+    expect(() => ledger.appendEvent({ type: "x", payload: { a: () => 1 } })).toThrow("invalid_payload");
+    expect(() => ledger.appendEvent({ type: "x", payload: { a: [1, undefined] } })).toThrow("invalid_payload");
+    // A fully JSON-safe nested payload is accepted and reads back identically.
+    const entry = ledger.appendEvent({ type: "x", payload: { a: { b: [1, "two", true, null] } } });
+    expect(ledger.readEvents()).toContainEqual(entry);
+  });
+
+  it("is append-only: the module source issues no UPDATE or DELETE against the ledger", () => {
+    const source = readFileSync("packages/gittensory-miner/lib/event-ledger.js", "utf8");
+    expect(source).not.toMatch(/\b(UPDATE|DELETE)\b/i);
+  });
+});