fix: route all agent loopback calls through internal_api_base() helper (#3322)

#2753 made the agent loopback base port-configurable but only for
_COOKBOOK_BASE in tool_implementations. Several other in-process loopback
calls still hardcoded http://localhost:7000 and broke off port 7000:
cookbook_serve_lifecycle (model-endpoints x2, shell/exec), builtin_actions
(model/serve), task_routes (calendar x3), and the gallery/email calls in
tool_implementations.

Extract the resolution (ODYSSEUS_INTERNAL_BASE / APP_PORT / 7000 fallback,
127.0.0.1 to avoid IPv6 ambiguity) into core.constants.internal_api_base()
and route every call site through it. Rename the now-misnamed _COOKBOOK_BASE
to _INTERNAL_BASE since it serves gallery/email/calendar/serve too. Adds a
test for the resolver plus a regression guard against reintroducing the
literal.

Part of #2752.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_internal_api_base.py

@@ -0,0 +1,52 @@
+"""internal_api_base() resolution + a guard that loopback call sites use it."""
+import importlib
+import pathlib
+
+import pytest
+
+import core.constants as cc
+
+
+def _base(monkeypatch, **env):
+    for k in ("ODYSSEUS_INTERNAL_BASE", "APP_PORT"):
+        monkeypatch.delenv(k, raising=False)
+    for k, v in env.items():
+        monkeypatch.setenv(k, v)
+    return cc.internal_api_base()
+
+
+def test_default_is_legacy_7000(monkeypatch):
+    assert _base(monkeypatch) == "http://127.0.0.1:7000"
+
+
+def test_app_port_is_honored(monkeypatch):
+    assert _base(monkeypatch, APP_PORT="7860") == "http://127.0.0.1:7860"
+
+
+def test_explicit_override_wins_and_is_stripped(monkeypatch):
+    # Override beats APP_PORT and trailing slash is trimmed.
+    assert _base(monkeypatch, APP_PORT="7860",
+                 ODYSSEUS_INTERNAL_BASE="https://proxy.example/") == "https://proxy.example"
+
+
+def test_uses_127_not_localhost(monkeypatch):
+    # 127.0.0.1 avoids IPv6/DNS ambiguity for the strictly-local loopback.
+    assert "localhost" not in _base(monkeypatch)
+
+
+def test_no_hardcoded_loopback_left_in_call_sites():
+    # Regression guard: the converted files must not reintroduce the literal.
+    root = pathlib.Path(__file__).resolve().parent.parent
+    for rel in (
+        "src/tool_implementations.py",
+        "src/cookbook_serve_lifecycle.py",
+        "src/builtin_actions.py",
+        "routes/task_routes.py",
+    ):
+        text = (root / rel).read_text(encoding="utf-8")
+        # Allow it only inside comments; flag any code occurrence.
+        for ln in text.splitlines():
+            stripped = ln.strip()
+            if stripped.startswith("#"):
+                continue
+            assert "localhost:7000" not in ln, f"{rel}: hardcoded loopback URL: {ln.strip()}"