diff --git a/src/cli/commands/embed.ts b/src/cli/commands/embed.ts
index 7ad46a10c..c4b00e2e7 100644
--- a/src/cli/commands/embed.ts
+++ b/src/cli/commands/embed.ts
@@ -11,9 +11,9 @@ import {
 import { info, warn } from '../../infrastructure/logger.js';
 import type { CommandDefinition } from '../types.js';
 
-function resolveStickyModel(dbPath: string | undefined): string | null {
+function resolveStickyModel(dbPath: string | undefined, rootDir: string): string | null {
   try {
-    const db = openReadonlyOrFail(dbPath, resolveBusyTimeoutMs(dbPath));
+    const db = openReadonlyOrFail(dbPath, resolveBusyTimeoutMs(dbPath ?? rootDir), rootDir);
     try {
       const storedName = getEmbeddingMeta(db, 'model');
       if (!storedName) return null;
@@ -47,7 +47,7 @@ export const command: CommandDefinition = {
       `Embedding strategy: ${EMBEDDING_STRATEGIES.join(', ')}. "structured" uses graph context (callers/callees), "source" embeds raw code`,
       'structured',
     ],
-    ['-d, --db <path>', 'Path to graph.db'],
+    ['-d, --db <path>', 'Path to graph.db (default: <dir>/.codegraph/graph.db)'],
   ],
   validate([_dir], opts, ctx) {
     if (!(EMBEDDING_STRATEGIES as readonly string[]).includes(opts.strategy)) {
@@ -85,7 +85,7 @@ export const command: CommandDefinition = {
       // before execute() runs — but keeps this branch type-safe.
       model = DEFAULT_MODEL;
     } else {
-      const sticky = resolveStickyModel(dbPath);
+      const sticky = resolveStickyModel(dbPath, root);
       if (sticky) {
         info(
           `Reusing previously-stored embedding model "${sticky}". Pass --model to switch, or set embeddings.model in your config.`,
diff --git a/src/db/connection.ts b/src/db/connection.ts
index 7c85980ce..c8321c6ef 100644
--- a/src/db/connection.ts
+++ b/src/db/connection.ts
@@ -303,13 +303,16 @@ function resolveDbSearchCeiling(rawCeiling: string | null): string | null {
   }
 }
 
-/** Resolve symlinks in cwd (e.g. macOS /var → /private/var) so dir matches ceiling from git. */
-function resolveDbSearchStartDir(): string {
+/**
+ * Resolve symlinks in the search start dir (e.g. macOS /var → /private/var) so
+ * it matches the ceiling from git. Defaults to cwd when no `dir` hint is given.
+ */
+function resolveDbSearchStartDir(dir: string = process.cwd()): string {
   try {
-    return fs.realpathSync(process.cwd());
+    return fs.realpathSync(dir);
   } catch (e) {
-    debug(`realpathSync failed for cwd: ${toErrorMessage(e)}`);
-    return process.cwd();
+    debug(`realpathSync failed for "${dir}": ${toErrorMessage(e)}`);
+    return dir;
   }
 }
 
@@ -342,24 +345,40 @@ function walkUpForDbPath(startDir: string, ceiling: string | null): string | nul
   }
 }
 
-export function findDbPath(customPath?: string): string {
+/**
+ * Locate `.codegraph/graph.db` for the current command.
+ *
+ * When `customPath` is set (e.g. `--db`), it wins outright.
+ * Otherwise the search starts at `rootDirHint` when the caller has one
+ * (e.g. the positional `dir` argument on commands like `embed [dir]`) —
+ * mirroring `build [dir]`'s convention of resolving the DB relative to
+ * that directory — and falls back to `process.cwd()` when there is no hint,
+ * walking upward toward the enclosing git repo root either way.
+ */
+export function findDbPath(customPath?: string, rootDirHint?: string): string {
   if (customPath) {
     return resolveCustomDbPath(customPath);
   }
-  const ceiling = resolveDbSearchCeiling(findRepoRoot());
-  const startDir = resolveDbSearchStartDir();
+  const ceiling = resolveDbSearchCeiling(findRepoRoot(rootDirHint));
+  const startDir = resolveDbSearchStartDir(rootDirHint);
   const found = walkUpForDbPath(startDir, ceiling);
   if (found) return found;
-  const base = ceiling || process.cwd();
+  const base = rootDirHint || ceiling || process.cwd();
   return path.join(base, '.codegraph', 'graph.db');
 }
 
-/** Open a database in readonly mode, with a user-friendly error if the DB doesn't exist. */
+/**
+ * Open a database in readonly mode, with a user-friendly error if the DB doesn't exist.
+ * `rootDirHint` is forwarded to `findDbPath()` for callers that know the project
+ * root (e.g. a command's positional `dir` argument) but weren't passed an explicit
+ * `--db`; it has no effect when `customPath` is set.
+ */
 export function openReadonlyOrFail(
   customPath?: string,
   busyTimeoutMs: number = DEFAULTS.db.busyTimeoutMs,
+  rootDirHint?: string,
 ): BetterSqlite3Database {
-  const dbPath = findDbPath(customPath);
+  const dbPath = findDbPath(customPath, rootDirHint);
   if (!fs.existsSync(dbPath)) {
     throw new DbError(
       `No codegraph database found at ${dbPath}.\nRun "codegraph build" first to analyze your codebase.`,
diff --git a/src/domain/search/generator.ts b/src/domain/search/generator.ts
index 61f5e037d..44d04a0a5 100644
--- a/src/domain/search/generator.ts
+++ b/src/domain/search/generator.ts
@@ -226,7 +226,10 @@ export async function buildEmbeddings(
   options: BuildEmbeddingsOptions = {},
 ): Promise<void> {
   const strategy = options.strategy || 'structured';
-  const dbPath = customDbPath || findDbPath(undefined);
+  // Search from rootDir (mirrors build's <rootDir>/.codegraph/graph.db convention),
+  // not process.cwd() — otherwise embed silently attaches to whatever unrelated
+  // .codegraph/graph.db happens to be found walking up from the current directory.
+  const dbPath = customDbPath || findDbPath(undefined, rootDir);
 
   if (!fs.existsSync(dbPath)) {
     throw new DbError(
diff --git a/tests/search/embedding-strategy.test.ts b/tests/search/embedding-strategy.test.ts
index f7a79f934..21dd723ef 100644
--- a/tests/search/embedding-strategy.test.ts
+++ b/tests/search/embedding-strategy.test.ts
@@ -459,6 +459,79 @@ describe('embed resolves source files from DB root, not cwd (#983)', () => {
   });
 });
 
+describe('buildEmbeddings resolves default DB from rootDir, not cwd (#1869)', () => {
+  let targetDir: string, unrelatedCwdDir: string, targetDbPath: string, unrelatedDbPath: string;
+  let originalCwd: string;
+
+  beforeAll(() => {
+    // The project embed is asked to operate on (positional `dir`, no --db).
+    targetDir = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-embed1869-target-'));
+    // An unrelated directory that happens to have its own graph.db — simulates
+    // running `embed <dir>` from inside a different, larger repo checkout.
+    unrelatedCwdDir = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-embed1869-cwd-'));
+
+    fs.writeFileSync(path.join(targetDir, 'c.js'), 'export function gamma() { return 3; }\n');
+
+    const targetDbDir = path.join(targetDir, '.codegraph');
+    fs.mkdirSync(targetDbDir, { recursive: true });
+    targetDbPath = path.join(targetDbDir, 'graph.db');
+    const targetDb = new Database(targetDbPath);
+    targetDb.pragma('journal_mode = WAL');
+    initSchema(targetDb);
+    insertNode(targetDb, 'gamma', 'function', 'c.js', 1, 1);
+    targetDb
+      .prepare('INSERT OR REPLACE INTO build_meta (key, value) VALUES (?, ?)')
+      .run('root_dir', path.resolve(targetDir));
+    targetDb.close();
+
+    // A DB at the unrelated cwd, which must never be touched by this run.
+    const unrelatedDbDir = path.join(unrelatedCwdDir, '.codegraph');
+    fs.mkdirSync(unrelatedDbDir, { recursive: true });
+    unrelatedDbPath = path.join(unrelatedDbDir, 'graph.db');
+    const unrelatedDb = new Database(unrelatedDbPath);
+    unrelatedDb.pragma('journal_mode = WAL');
+    initSchema(unrelatedDb);
+    unrelatedDb.close();
+
+    originalCwd = process.cwd();
+  });
+
+  afterAll(() => {
+    try {
+      process.chdir(originalCwd);
+    } catch {
+      /* ignore */
+    }
+    if (targetDir) fs.rmSync(targetDir, { recursive: true, force: true });
+    if (unrelatedCwdDir) fs.rmSync(unrelatedCwdDir, { recursive: true, force: true });
+  });
+
+  test('writes to <dir>/.codegraph/graph.db, not the cwd DB, when --db is omitted', async () => {
+    EMBEDDED_TEXTS.length = 0;
+    process.chdir(unrelatedCwdDir);
+
+    // Simulates `codegraph embed <targetDir>` with no --db flag: buildEmbeddings
+    // must default the DB path relative to targetDir, exactly like `build <dir>`.
+    await buildEmbeddings(targetDir, 'minilm', undefined);
+
+    expect(EMBEDDED_TEXTS.length).toBe(1);
+
+    const targetDb = new Database(targetDbPath, { readonly: true });
+    const targetCount = targetDb.prepare('SELECT COUNT(*) as c FROM embeddings').get().c;
+    targetDb.close();
+    expect(targetCount).toBe(1);
+
+    // The unrelated cwd DB was never opened for writing — it doesn't even
+    // have an `embeddings` table, since buildEmbeddings creates it lazily.
+    const unrelatedDb = new Database(unrelatedDbPath, { readonly: true });
+    const unrelatedTables = unrelatedDb
+      .prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = 'embeddings'")
+      .all();
+    unrelatedDb.close();
+    expect(unrelatedTables).toHaveLength(0);
+  });
+});
+
 describe('context window overflow detection', () => {
   let bigDir: string, bigDbPath: string;
 
diff --git a/tests/unit/db.test.ts b/tests/unit/db.test.ts
index abd5895f7..ce9b4b11c 100644
--- a/tests/unit/db.test.ts
+++ b/tests/unit/db.test.ts
@@ -576,6 +576,90 @@ describe('findDbPath with git ceiling', () => {
   });
 });
 
+describe('findDbPath with rootDirHint (#1869)', () => {
+  let targetDir: string, unrelatedCwdDir: string;
+
+  beforeAll(() => {
+    // A project with its own graph.db — the intended target (e.g. `embed <dir>`'s
+    // positional argument).
+    targetDir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-roothint-target-'));
+    fs.mkdirSync(path.join(targetDir, '.codegraph'), { recursive: true });
+    fs.writeFileSync(path.join(targetDir, '.codegraph', 'graph.db'), '');
+    // An unrelated directory with its OWN graph.db, standing in for whatever
+    // cwd the command happens to be invoked from.
+    unrelatedCwdDir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-roothint-cwd-'));
+    fs.mkdirSync(path.join(unrelatedCwdDir, '.codegraph'), { recursive: true });
+    fs.writeFileSync(path.join(unrelatedCwdDir, '.codegraph', 'graph.db'), '');
+    // Resolve symlinks (macOS /tmp → /private/tmp) so expected paths match
+    // findDbPath's internal realpathSync'd start dir.
+    targetDir = fs.realpathSync(targetDir);
+    unrelatedCwdDir = fs.realpathSync(unrelatedCwdDir);
+  });
+
+  afterAll(() => {
+    fs.rmSync(targetDir, { recursive: true, force: true });
+    fs.rmSync(unrelatedCwdDir, { recursive: true, force: true });
+  });
+
+  afterEach(() => {
+    _resetRepoRootCache();
+  });
+
+  it('searches from rootDirHint instead of cwd when no customPath is given', () => {
+    const origCwd = process.cwd;
+    process.cwd = () => unrelatedCwdDir;
+    try {
+      _resetRepoRootCache();
+      const result = findDbPath(undefined, targetDir);
+      expect(result).toBe(path.join(targetDir, '.codegraph', 'graph.db'));
+    } finally {
+      process.cwd = origCwd;
+    }
+  });
+
+  it('still lets an explicit customPath win over rootDirHint', () => {
+    const explicit = path.join(tmpDir, 'explicit-override.db');
+    const result = findDbPath(explicit, targetDir);
+    expect(result).toBe(path.resolve(explicit));
+  });
+
+  it('falls back to cwd when rootDirHint is not provided (unchanged default behavior)', () => {
+    const origCwd = process.cwd;
+    process.cwd = () => unrelatedCwdDir;
+    try {
+      _resetRepoRootCache();
+      const result = findDbPath();
+      expect(result).toBe(path.join(unrelatedCwdDir, '.codegraph', 'graph.db'));
+    } finally {
+      process.cwd = origCwd;
+    }
+  });
+
+  it('prefers rootDirHint over the git ceiling for the no-DB-found default path (Greptile review)', () => {
+    // rootDirHint is a subdirectory *inside* a git repo, with no existing
+    // .codegraph/graph.db anywhere between it and the repo root — so
+    // walkUpForDbPath finds nothing and the fallback default-path branch
+    // runs. Before the fix, `ceiling || rootDirHint || cwd` let the git
+    // ceiling win whenever one existed, producing <git-root>/.codegraph/graph.db
+    // instead of build's own <rootDirHint>/.codegraph/graph.db convention.
+    const repoRoot = fs.mkdtempSync(path.join(tmpDir, 'cg-hint-priority-'));
+    execFileSyncForSetup('git', ['init'], { cwd: repoRoot, stdio: 'pipe' });
+    const subDir = path.join(repoRoot, 'packages', 'sub');
+    fs.mkdirSync(subDir, { recursive: true });
+    const resolvedRepoRoot = fs.realpathSync(repoRoot);
+    const resolvedSubDir = fs.realpathSync(subDir);
+
+    _resetRepoRootCache();
+    try {
+      const result = findDbPath(undefined, resolvedSubDir);
+      expect(result).toBe(path.join(resolvedSubDir, '.codegraph', 'graph.db'));
+      expect(result).not.toBe(path.join(resolvedRepoRoot, '.codegraph', 'graph.db'));
+    } finally {
+      _resetRepoRootCache();
+    }
+  });
+});
+
 describe('openReadonlyOrFail', () => {
   it('throws DbError when DB does not exist', () => {
     expect.assertions(4);
@@ -616,4 +700,37 @@ describe('openReadonlyOrFail', () => {
     expect(timeout).toBe(5000);
     readDb.close();
   });
+
+  it('resolves against rootDirHint instead of cwd when no explicit path is given (#1869)', () => {
+    const targetDir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-readonly-roothint-target-'));
+    const unrelatedCwdDir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-readonly-roothint-cwd-'));
+    try {
+      const dbDir = path.join(targetDir, '.codegraph');
+      fs.mkdirSync(dbDir, { recursive: true });
+      const db = openDb(path.join(dbDir, 'graph.db'));
+      initSchema(db);
+      closeDb(db);
+      // A DB at the unrelated cwd must be ignored in favor of rootDirHint.
+      fs.mkdirSync(path.join(unrelatedCwdDir, '.codegraph'), { recursive: true });
+      fs.writeFileSync(path.join(unrelatedCwdDir, '.codegraph', 'graph.db'), '');
+
+      const origCwd = process.cwd;
+      process.cwd = () => unrelatedCwdDir;
+      try {
+        _resetRepoRootCache();
+        const readDb = openReadonlyOrFail(undefined, undefined, targetDir);
+        const tables = readDb
+          .prepare("SELECT name FROM sqlite_master WHERE type='table'")
+          .all()
+          .map((r) => r.name);
+        expect(tables).toContain('nodes');
+        readDb.close();
+      } finally {
+        process.cwd = origCwd;
+      }
+    } finally {
+      fs.rmSync(targetDir, { recursive: true, force: true });
+      fs.rmSync(unrelatedCwdDir, { recursive: true, force: true });
+    }
+  });
 });
diff --git a/tests/unit/embed-command.test.ts b/tests/unit/embed-command.test.ts
index 8c85595aa..82476a327 100644
--- a/tests/unit/embed-command.test.ts
+++ b/tests/unit/embed-command.test.ts
@@ -1,3 +1,4 @@
+import path from 'node:path';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 vi.mock('../../src/domain/search/index.js', async (importOriginal) => {
@@ -8,11 +9,13 @@ vi.mock('../../src/db/index.js', () => ({
   openReadonlyOrFail: vi.fn(() => {
     throw new Error('no db in this test');
   }),
+  resolveBusyTimeoutMs: vi.fn(() => 5000),
 }));
 vi.mock('../../src/db/repository/embeddings.js', () => ({ getEmbeddingMeta: vi.fn() }));
 
 const { command } = await import('../../src/cli/commands/embed.js');
 const { buildEmbeddings } = await import('../../src/domain/search/index.js');
+const { openReadonlyOrFail } = await import('../../src/db/index.js');
 
 function fakeCtx(embeddings: Record<string, unknown>, llm: Record<string, unknown> = {}) {
   return {
@@ -81,6 +84,7 @@ describe('embed command validate()', () => {
 describe('embed command execute()', () => {
   beforeEach(() => {
     vi.mocked(buildEmbeddings).mockClear();
+    vi.mocked(openReadonlyOrFail).mockClear();
   });
 
   afterEach(() => {
@@ -115,4 +119,21 @@ describe('embed command execute()', () => {
     const [, , , options] = vi.mocked(buildEmbeddings).mock.calls[0]!;
     expect(options.remote).toBeUndefined();
   });
+
+  it('resolves the sticky-model DB lookup and buildEmbeddings against the positional dir, not cwd (#1869)', async () => {
+    const ctx = fakeCtx({});
+    const targetDir = path.join('some', 'other', 'project');
+
+    await command.execute!([targetDir], { strategy: 'structured' } as never, ctx);
+
+    // resolveStickyModel() must open the DB relative to the resolved dir, not
+    // whatever the process's cwd happens to be.
+    expect(openReadonlyOrFail).toHaveBeenCalledTimes(1);
+    const [, , rootDirHint] = vi.mocked(openReadonlyOrFail).mock.calls[0]!;
+    expect(rootDirHint).toBe(path.resolve(targetDir));
+
+    expect(buildEmbeddings).toHaveBeenCalledTimes(1);
+    const [rootArg] = vi.mocked(buildEmbeddings).mock.calls[0]!;
+    expect(rootArg).toBe(path.resolve(targetDir));
+  });
 });