fix(init): split --auto-mine from --yes; show file-count estimate before mine prompt

Reviewer feedback on the previous commit flagged two real problems:

1. Overloading --yes to also auto-mine was a silent behaviour change for
   scripted callers. Today --yes only auto-accepts entities — making it
   ALSO trigger a multi-minute ChromaDB write breaks every script that
   currently runs `mempalace init --yes <dir>` for the fast non-interactive
   entity path. Add a separate `--auto-mine` flag instead. Combinations:

     mempalace init --yes <dir>              # entities auto, STILL prompt mine
     mempalace init --auto-mine <dir>        # prompt entities, skip mine prompt
     mempalace init --yes --auto-mine <dir>  # fully non-interactive

   --yes behaviour is now identical to pre-PR.

2. The mine prompt was firing without telling the user how big the job
   was. On a real corpus mine takes minutes-to-tens-of-minutes; hitting
   Enter on default-Y with no size cue is a footgun. Show a one-line
   estimate computed from scan_project (the same walk we hand into mine)
   BEFORE the prompt:

     ~423 files (~12 MB) would be mined into this palace.
     Mine this directory now? [Y/n]

   The estimate uses a single corpus walk: scan_project's output is
   passed into mine() via a new optional files= kwarg, so we never walk
   the tree twice.

Tests: replaced the old "--yes auto-mines" assertion with a regression
guard that --yes alone STILL prompts; added coverage for --auto-mine
alone, --yes --auto-mine together, and the pre-prompt estimate line.

tests/test_cli.py

@@ -152,8 +152,8 @@ def test_cmd_init_with_entities_zero_total(mock_config_cls, tmp_path, capsys):
 # ── _maybe_run_mine_after_init (init → mine prompt, #1181) ─────────────
 
 
-def _init_args(tmp_path, *, yes=False):
-    return argparse.Namespace(dir=str(tmp_path), yes=yes)
+def _init_args(tmp_path, *, yes=False, auto_mine=False):
+    return argparse.Namespace(dir=str(tmp_path), yes=yes, auto_mine=auto_mine)
 
 
 def _fake_cfg(tmp_path):
@@ -162,26 +162,41 @@ def _fake_cfg(tmp_path):
     return cfg
 
 
+def _fake_scanned(tmp_path, n=3):
+    """Build n real Path objects with stat()-able sizes for the scan estimate."""
+    paths = []
+    for i in range(n):
+        p = tmp_path / f"f{i}.txt"
+        p.write_text("x" * 1024)  # 1 KB each
+        paths.append(p)
+    return paths
+
+
 def test_maybe_run_mine_prompt_accepted_runs_mine(tmp_path):
     """Empty / 'y' / 'yes' on the prompt triggers mine() in-process."""
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=False)
+    args = _init_args(tmp_path, yes=False, auto_mine=False)
     cfg = _fake_cfg(tmp_path)
+    scanned = _fake_scanned(tmp_path, n=3)
     with (
         patch("mempalace.miner.mine") as mock_mine,
-        patch("mempalace.miner.scan_project", return_value=["a", "b", "c"]),
+        patch("mempalace.miner.scan_project", return_value=scanned),
         patch("builtins.input", return_value=""),
     ):
         _maybe_run_mine_after_init(args, cfg)
-        mock_mine.assert_called_once_with(project_dir=str(tmp_path), palace_path=cfg.palace_path)
+        mock_mine.assert_called_once_with(
+            project_dir=str(tmp_path),
+            palace_path=cfg.palace_path,
+            files=scanned,
+        )
 
 
 def test_maybe_run_mine_prompt_yes_accepted_runs_mine(tmp_path):
     """Explicit 'y' answer also runs mine()."""
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=False)
+    args = _init_args(tmp_path, yes=False, auto_mine=False)
     cfg = _fake_cfg(tmp_path)
     with (
         patch("mempalace.miner.mine") as mock_mine,
@@ -196,7 +211,7 @@ def test_maybe_run_mine_prompt_declined_prints_hint(tmp_path, capsys):
     """'n' answer skips mine() and prints the resume hint."""
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=False)
+    args = _init_args(tmp_path, yes=False, auto_mine=False)
     cfg = _fake_cfg(tmp_path)
     with (
         patch("mempalace.miner.mine") as mock_mine,
@@ -210,11 +225,52 @@ def test_maybe_run_mine_prompt_declined_prints_hint(tmp_path, capsys):
     assert "Skipped" in out
 
 
-def test_maybe_run_mine_yes_flag_skips_prompt_and_mines(tmp_path):
-    """`--yes` runs mine() automatically without calling input()."""
+def test_maybe_run_mine_yes_alone_still_prompts(tmp_path):
+    """`--yes` is scoped to entity auto-accept and MUST still prompt for mine.
+
+    Regression guard for the flag-overload review feedback on #1183: extending
+    `--yes` to also auto-mine would silently change behaviour for scripted
+    callers and turn a fast command into a minutes-long ChromaDB write.
+    """
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=True)
+    args = _init_args(tmp_path, yes=True, auto_mine=False)
+    cfg = _fake_cfg(tmp_path)
+    with (
+        patch("mempalace.miner.mine") as mock_mine,
+        patch("mempalace.miner.scan_project", return_value=[]),
+        patch("builtins.input", return_value="n") as mock_input,
+    ):
+        _maybe_run_mine_after_init(args, cfg)
+        mock_input.assert_called_once()  # the prompt MUST fire
+        mock_mine.assert_not_called()
+
+
+def test_maybe_run_mine_auto_mine_skips_prompt(tmp_path):
+    """`--auto-mine` runs mine() automatically without calling input()."""
+    from mempalace.cli import _maybe_run_mine_after_init
+
+    args = _init_args(tmp_path, yes=False, auto_mine=True)
+    cfg = _fake_cfg(tmp_path)
+    scanned = _fake_scanned(tmp_path, n=2)
+    with (
+        patch("mempalace.miner.mine") as mock_mine,
+        patch("mempalace.miner.scan_project", return_value=scanned),
+        patch("builtins.input", side_effect=AssertionError("input() must not be called")),
+    ):
+        _maybe_run_mine_after_init(args, cfg)
+        mock_mine.assert_called_once_with(
+            project_dir=str(tmp_path),
+            palace_path=cfg.palace_path,
+            files=scanned,
+        )
+
+
+def test_maybe_run_mine_yes_and_auto_mine_fully_noninteractive(tmp_path):
+    """`--yes --auto-mine` together: never call input(), always mine."""
+    from mempalace.cli import _maybe_run_mine_after_init
+
+    args = _init_args(tmp_path, yes=True, auto_mine=True)
     cfg = _fake_cfg(tmp_path)
     with (
         patch("mempalace.miner.mine") as mock_mine,
@@ -222,14 +278,14 @@ def test_maybe_run_mine_yes_flag_skips_prompt_and_mines(tmp_path):
         patch("builtins.input", side_effect=AssertionError("input() must not be called")),
     ):
         _maybe_run_mine_after_init(args, cfg)
-        mock_mine.assert_called_once_with(project_dir=str(tmp_path), palace_path=cfg.palace_path)
+        mock_mine.assert_called_once()
 
 
 def test_maybe_run_mine_eof_on_stdin_treated_as_decline(tmp_path, capsys):
     """Piped / non-interactive stdin (EOFError) declines without crashing."""
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=False)
+    args = _init_args(tmp_path, yes=False, auto_mine=False)
     cfg = _fake_cfg(tmp_path)
     with (
         patch("mempalace.miner.mine") as mock_mine,
@@ -245,7 +301,7 @@ def test_maybe_run_mine_failure_surfaces_via_exit(tmp_path, capsys):
     """Mine errors are not swallowed — they exit non-zero with an error line."""
     from mempalace.cli import _maybe_run_mine_after_init
 
-    args = _init_args(tmp_path, yes=True)
+    args = _init_args(tmp_path, yes=False, auto_mine=True)
     cfg = _fake_cfg(tmp_path)
     with (
         patch("mempalace.miner.mine", side_effect=RuntimeError("boom")),
@@ -258,6 +314,38 @@ def test_maybe_run_mine_failure_surfaces_via_exit(tmp_path, capsys):
     assert "boom" in err
 
 
+def test_maybe_run_mine_estimate_appears_before_prompt(tmp_path, capsys):
+    """The file-count + size estimate line MUST render BEFORE the prompt.
+
+    Required by the spec: hitting Enter on a default-Y prompt with no size
+    info is a footgun on a real corpus where mine takes minutes. The user
+    must see scope before being asked to confirm.
+    """
+    from mempalace.cli import _maybe_run_mine_after_init
+
+    args = _init_args(tmp_path, yes=False, auto_mine=False)
+    cfg = _fake_cfg(tmp_path)
+    scanned = _fake_scanned(tmp_path, n=4)  # 4 files * 1 KB each
+    captured_when_prompted = {}
+
+    def fake_input(prompt):
+        # Snapshot what stdout looked like at the moment the prompt fires.
+        captured_when_prompted["stdout"] = capsys.readouterr().out
+        return "n"
+
+    with (
+        patch("mempalace.miner.mine"),
+        patch("mempalace.miner.scan_project", return_value=scanned),
+        patch("builtins.input", side_effect=fake_input),
+    ):
+        _maybe_run_mine_after_init(args, cfg)
+
+    pre_prompt = captured_when_prompted["stdout"]
+    assert "4 files" in pre_prompt, f"file count missing from pre-prompt output: {pre_prompt!r}"
+    assert "MB" in pre_prompt, f"size estimate missing from pre-prompt output: {pre_prompt!r}"
+    assert "would be mined" in pre_prompt
+
+
 # ── cmd_mine ───────────────────────────────────────────────────────────