diff --git a/lib/project/discovery.py b/lib/project/discovery.py
index c05a8106..1ce106fc 100644
--- a/lib/project/discovery.py
+++ b/lib/project/discovery.py
@@ -1,12 +1,14 @@
 from __future__ import annotations
 
 import json
+import os
 from pathlib import Path
 import tempfile
 from typing import Any
 
 CCB_DIRNAME = '.ccb'
 WORKSPACE_BINDING_FILENAME = '.ccb-workspace.json'
+CCB_PROJECT_DIR_ENV = 'CCB_PROJECT_DIR'
 
 
 class ProjectDiscoveryError(ValueError):
@@ -22,6 +24,9 @@ def global_ccb_dir() -> Path:
 
 
 def find_current_project_anchor(start_dir: Path) -> Path | None:
+    env_anchor = _env_project_anchor()
+    if env_anchor is not None:
+        return env_anchor
     current = _resolved_dir(start_dir)
     if _project_anchor_dir(current) is None:
         return None
@@ -29,6 +34,9 @@ def find_current_project_anchor(start_dir: Path) -> Path | None:
 
 
 def find_nearest_project_anchor(start_dir: Path) -> Path | None:
+    env_anchor = _env_project_anchor()
+    if env_anchor is not None:
+        return env_anchor
     current = _resolved_dir(start_dir)
     for root in _search_roots(current):
         if _project_anchor_dir(root) is None:
@@ -40,6 +48,19 @@ def find_nearest_project_anchor(start_dir: Path) -> Path | None:
     return None
 
 
+def _env_project_anchor() -> Path | None:
+    raw = os.environ.get(CCB_PROJECT_DIR_ENV)
+    if not raw:
+        return None
+    try:
+        candidate = _resolved_dir(Path(raw))
+    except Exception:
+        return None
+    if _project_anchor_dir(candidate) is None:
+        return None
+    return candidate
+
+
 def find_parent_project_anchor_dir(start_dir: Path) -> Path | None:
     current = _resolved_dir(start_dir)
     for root in current.parents:
diff --git a/test/test_project_discovery_env.py b/test/test_project_discovery_env.py
new file mode 100644
index 00000000..646e9185
--- /dev/null
+++ b/test/test_project_discovery_env.py
@@ -0,0 +1,84 @@
+"""Tests for CCB_PROJECT_DIR env var support in project discovery."""
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+from project.discovery import (
+    CCB_PROJECT_DIR_ENV,
+    find_current_project_anchor,
+    find_nearest_project_anchor,
+)
+
+
+def _make_ccb_dir(parent: Path) -> Path:
+    (parent / '.ccb').mkdir(parents=True, exist_ok=True)
+    return parent
+
+
+class TestCcbProjectDirEnv:
+    def test_env_unset_walks_cwd(self, monkeypatch, tmp_path):
+        monkeypatch.delenv(CCB_PROJECT_DIR_ENV, raising=False)
+        _make_ccb_dir(tmp_path)
+        nested = tmp_path / 'nested' / 'deeper'
+        nested.mkdir(parents=True)
+        assert find_nearest_project_anchor(nested) == tmp_path.resolve()
+
+    def test_env_set_with_valid_ccb_dir_wins_over_cwd(self, monkeypatch, tmp_path):
+        env_project = _make_ccb_dir(tmp_path / 'env_project')
+        cwd_project = _make_ccb_dir(tmp_path / 'cwd_project')
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(env_project))
+        assert find_nearest_project_anchor(cwd_project) == env_project.resolve()
+
+    def test_env_set_with_path_that_has_no_ccb_dir_falls_through(self, monkeypatch, tmp_path):
+        env_path = tmp_path / 'empty_dir'
+        env_path.mkdir()
+        cwd_project = _make_ccb_dir(tmp_path / 'cwd_project')
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(env_path))
+        assert find_nearest_project_anchor(cwd_project) == cwd_project.resolve()
+
+    def test_env_set_with_nonexistent_path_falls_through(self, monkeypatch, tmp_path):
+        cwd_project = _make_ccb_dir(tmp_path / 'cwd_project')
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(tmp_path / 'does_not_exist'))
+        assert find_nearest_project_anchor(cwd_project) == cwd_project.resolve()
+
+    def test_env_set_to_empty_string_treated_as_unset(self, monkeypatch, tmp_path):
+        cwd_project = _make_ccb_dir(tmp_path / 'cwd_project')
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, '')
+        assert find_nearest_project_anchor(cwd_project) == cwd_project.resolve()
+
+    def test_env_bypasses_dangerous_root_check(self, monkeypatch, tmp_path):
+        """User explicit intent via env overrides the $HOME-like dangerous check."""
+        env_project = _make_ccb_dir(tmp_path)
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(env_project))
+        unrelated = tmp_path.parent
+        assert find_nearest_project_anchor(unrelated) == env_project.resolve()
+
+
+class TestFindCurrentProjectAnchorEnv:
+    """Env var support for the bootstrap_if_missing=True code path.
+
+    ccb ps / ccb ask / etc. use `find_current_project_anchor` when
+    bootstrap-if-missing is enabled. Without env support here, callers
+    from a non-project cwd would trigger auto-bootstrap even with
+    CCB_PROJECT_DIR set.
+    """
+
+    def test_env_unset_returns_none_for_non_project_cwd(self, monkeypatch, tmp_path):
+        monkeypatch.delenv(CCB_PROJECT_DIR_ENV, raising=False)
+        assert find_current_project_anchor(tmp_path) is None
+
+    def test_env_set_returns_env_path_even_from_non_project_cwd(self, monkeypatch, tmp_path):
+        env_project = _make_ccb_dir(tmp_path / 'env_project')
+        non_project_cwd = tmp_path / 'elsewhere'
+        non_project_cwd.mkdir()
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(env_project))
+        assert find_current_project_anchor(non_project_cwd) == env_project.resolve()
+
+    def test_env_set_falls_through_when_env_path_has_no_ccb_dir(self, monkeypatch, tmp_path):
+        env_path = tmp_path / 'no_ccb_here'
+        env_path.mkdir()
+        cwd_project = _make_ccb_dir(tmp_path / 'cwd_project')
+        monkeypatch.setenv(CCB_PROJECT_DIR_ENV, str(env_path))
+        assert find_current_project_anchor(cwd_project) == cwd_project.resolve()