fix(ai): install oMLX without Homebrew stopping to ask

stacklets/ai/hooks/on_install.py

@@ -24,6 +24,12 @@
 # third-party tap until that tap is trusted, so the trust step in
 # `_install_omlx_formula` is what stands between a working `stack up ai`
 # and an install that dies at the first brew command.
+# Homebrew 7 asks before an install that brings dependencies, and the
+# question is buried in `stack up ai`'s output, where a script or an agent
+# waits on it for good. The admin already said yes to setting up AI. Older
+# Homebrew ignores the variable, where it would refuse `--yes`.
+BREW_INSTALL = "HOMEBREW_NO_ASK=1 brew install"
+
 OMLX_TAP = "jundot/omlx"
 OMLX_TAP_URL = "https://github.com/jundot/omlx"
 WHISPER_MODEL = "ggml-large-v3-turbo.bin"
@@ -99,7 +105,7 @@ def _install_omlx_formula(ctx) -> None:
     except RuntimeError:
         dim("  (this Homebrew has no trust gate — nothing to do)")
 
-    ctx.shell_live("brew install omlx --with-grammar")
+    ctx.shell_live(f"{BREW_INSTALL} omlx --with-grammar")
 
 
 def install_omlx(ctx, state_dir: Path):
@@ -183,7 +189,7 @@ def _install_whisper(ctx, data_dir: Path, state_dir: Path):
 
     if missing:
         ctx.step(f"Installing build dependencies: {' '.join(missing)}...")
-        ctx.shell_live(f"brew install {' '.join(missing)}")
+        ctx.shell_live(f"{BREW_INSTALL} {' '.join(missing)}")
         done("Dependencies ready")
 
     # Clone source

tests/unit/stacklets/test_ai_omlx_install.py

@@ -72,7 +72,7 @@ def test_the_tap_is_trusted_before_the_install_runs(self):
         trust_at = next(i for i, c in enumerate(ctx.commands)
                         if c.startswith("brew trust"))
         install_at = next(i for i, c in enumerate(ctx.commands)
-                          if c.startswith("brew install omlx"))
+                          if "brew install omlx" in c)
         assert trust_at < install_at, "trusting after installing is too late"
 
     def test_the_tap_is_added_before_it_is_trusted(self):
@@ -90,7 +90,16 @@ def test_grammar_is_requested_so_json_mode_works(self):
         # formula installs a build whose JSON mode is broken.
         ctx = FakeCtx()
         _install_omlx_formula(ctx)
-        assert any(c == "brew install omlx --with-grammar" for c in ctx.commands)
+        assert any(c.endswith("brew install omlx --with-grammar") for c in ctx.commands)
+
+    def test_homebrew_does_not_stop_to_ask(self):
+        """Homebrew 7 asks before an install that brings dependencies. Deep
+        in `stack up ai` nobody expects that question, and a script or an
+        agent running it waits on it for good."""
+        ctx = FakeCtx()
+        _install_omlx_formula(ctx)
+        (install,) = [c for c in ctx.commands if "brew install" in c]
+        assert install.startswith("HOMEBREW_NO_ASK=1 ")
 
     def test_steps_are_separate_commands_not_one_chained_string(self):
         """Chained with `&&`, any failure reported the whole string, so a
@@ -105,4 +114,4 @@ def test_a_homebrew_without_a_trust_gate_still_installs(self):
         nothing to clear, so its absence is success, not a failed install."""
         ctx = FakeCtx(no_trust_subcommand=True)
         _install_omlx_formula(ctx)  # must not raise
-        assert any(c.startswith("brew install omlx") for c in ctx.commands)
+        assert any("brew install omlx" in c for c in ctx.commands)

tests/unit/stacklets/test_ai_start_guard.py

@@ -103,7 +103,7 @@ def test_a_missing_engine_is_installed(self, monkeypatch):
 
         on_start.run(ctx)
 
-        assert "brew install omlx --with-grammar" in ctx.shell_calls
+        assert any(c.endswith("brew install omlx --with-grammar") for c in ctx.shell_calls)
 
     def test_an_installed_engine_starts_normally(self, monkeypatch):
         monkeypatch.setattr(on_start.shutil, "which",