feat: deep-agent canvas, live observability, and multi-environment tooling

Self-hosted platform for building, testing, and shipping LangChain/LangGraph agents. Deep-agent sub-agents on the canvas, a live tracing/observability timeline, auto-provisioned built-in tools with import/export, per-environment tool variables, streamed evaluations, and per-user auth token forwarding.

apps/api/tests/test_cost.py

@@ -0,0 +1,25 @@
+"""Cost levers: accurate token counting + cheap-model defaults."""
+
+from __future__ import annotations
+
+from forge.engine.models import cheap_model_for_credentials, default_model_for_credentials
+from forge.tools.projection import count_tokens, estimate_tokens
+
+
+def test_count_tokens_nonzero_and_aliased():
+    n = count_tokens("hello world, this is a token counting test")
+    assert n > 0
+    assert estimate_tokens("hello world, this is a token counting test") == n  # alias
+
+
+def test_count_tokens_handles_objects_and_none():
+    assert count_tokens(None) == 0
+    assert count_tokens({"a": [1, 2, 3], "b": "text"}) > 0
+
+
+def test_cheap_model_prefers_provider_nano_tier():
+    assert cheap_model_for_credentials({"openai": "k"}) == "openai:gpt-4.1-nano"
+    assert cheap_model_for_credentials({"anthropic": "k"}) == "anthropic:claude-haiku-4-5"
+    assert cheap_model_for_credentials({}) is None
+    # the cheap model is distinct from the default (frontier-ish) model
+    assert cheap_model_for_credentials({"openai": "k"}) != default_model_for_credentials({"openai": "k"})