fix(vercel): keep pyproject.toml out of the upload so the build installs requirements.txt

Author: codebybilal18

.vercelignore

@@ -28,6 +28,19 @@
 /requirements-local.txt
 /requirements-dev.txt
 
+# Excluded so the build uses requirements.txt.
+#
+# Vercel's Python builder runs `uv lock` against pyproject.toml whenever the
+# file is present, and never looks at requirements.txt. This project is an
+# application, not a distributable package: pyproject.toml carries only ruff
+# and pytest configuration, so `uv lock` fails outright with
+#   error: No `project` table found in: /vercel/path0/pyproject.toml
+# Keeping it out of the upload restores the standard requirements.txt install.
+#
+# The alternative is a full [project] table duplicating every pin from
+# requirements.txt — a second dependency list to keep in sync, for no gain.
+/pyproject.toml
+
 /README.md
 /.venv/
 /.ruff_cache/

README.md

@@ -324,10 +324,17 @@ Import the repo at vercel.com/new. Project settings:
 
 Vercel resolves the entrypoint by scanning `app.py`/`index.py`/`main.py`/`server.py`/`wsgi.py`/
 `asgi.py` at the root and inside `src/`, `app/` and `api/`, then bundles the whole app as a single
-function. This repo declares it explicitly instead — `[tool.vercel] entrypoint` in
-[pyproject.toml](pyproject.toml) — so resolution order never matters, and
-[vercel.json](vercel.json) configures that same file. `tests/test_deployment_contract.py` fails if
-the two drift apart, or if a second module-level `app` appears anywhere.
+function. `app/main.py` is the only file in this repo exposing a module-level `app`, so resolution
+is unambiguous, and [vercel.json](vercel.json) configures that same path.
+
+Two packaging details that are easy to get wrong, both enforced by
+`tests/test_deployment_contract.py`:
+
+- **`pyproject.toml` is excluded from the upload** ([.vercelignore](.vercelignore)). Vercel runs
+  `uv lock` against it whenever it is present and never reads `requirements.txt`. Since this repo's
+  `pyproject.toml` holds only ruff and pytest config, leaving it in breaks the build.
+- **`.vercelignore` patterns are anchored with `/`.** It uses gitignore semantics, so an
+  unanchored `evals/` also matches `app/evals/` and strips a package the request path imports.
 
 Environment variables:
 

pyproject.toml

@@ -1,16 +1,10 @@
-# No [project] table on purpose.
+# Tool configuration only — no [project] table.
 #
-# Vercel's Python builder prefers pyproject.toml over requirements.txt when a
-# [project] table is present. This project is not a distributable package, so
-# that table declared no `dependencies` — and the build installed nothing,
-# leaving the deployed function to die with `ModuleNotFoundError: No module
-# named 'fastapi'`. Without it, requirements.txt is unambiguously the source.
-
-[tool.vercel]
-# Explicit beats inferred. Vercel otherwise scans app.py/index.py/main.py/... at
-# the root and inside src/, app/ and api/, and picks whichever it finds first —
-# a resolution order this repo should not depend on.
-entrypoint = "app.main:app"
+# This is an application, not a distributable package. Note that Vercel's Python
+# builder runs `uv lock` against this file whenever it is present and ignores
+# requirements.txt entirely, so it is excluded from the deployment upload in
+# .vercelignore. Adding a [project] table here without also listing every
+# runtime dependency will break the build.
 
 [tool.ruff]
 line-length = 100

tests/test_deployment_contract.py

@@ -17,6 +17,14 @@
 ROOT = Path(__file__).resolve().parents[1]
 
 
+def _vercelignore_lines() -> list[str]:
+    return [
+        line
+        for raw in (ROOT / ".vercelignore").read_text().splitlines()
+        if (line := raw.strip()) and not line.startswith("#")
+    ]
+
+
 def module_level_asgi_apps() -> list[str]:
     """Files assigning a module-level `app`, which is what Vercel's FastAPI
     preset scans for when choosing an entrypoint."""
@@ -50,37 +58,44 @@ def test_there_is_exactly_one_asgi_entrypoint():
     )
 
 
-def test_the_declared_entrypoint_matches_the_configured_function():
-    """pyproject.toml names the entrypoint; vercel.json configures the function
-    by resolved file path. If they drift, maxDuration silently applies to a file
-    that is not the entrypoint and every request hits the default timeout."""
+def test_vercel_json_configures_the_actual_entrypoint():
+    """vercel.json keys the function by resolved file path. If it names a file
+    that is not the entrypoint, maxDuration silently applies to nothing and slow
+    requests die at the default timeout instead."""
     import json
-    import re
-
-    pyproject = (ROOT / "pyproject.toml").read_text()
-    match = re.search(r'entrypoint\s*=\s*"([^"]+)"', pyproject)
-    assert match, "pyproject.toml must declare [tool.vercel] entrypoint"
-
-    module, _, attribute = match.group(1).partition(":")
-    entry_file = module.replace(".", "/") + ".py"
-    assert attribute == "app"
-    assert (ROOT / entry_file).exists(), f"{entry_file} does not exist"
 
     configured = list(json.loads((ROOT / "vercel.json").read_text())["functions"])
-    assert configured == [entry_file], (
-        f"vercel.json configures {configured} but the entrypoint is {entry_file}"
+    assert configured == module_level_asgi_apps(), (
+        f"vercel.json configures {configured}, but the ASGI entrypoint is "
+        f"{module_level_asgi_apps()}"
     )
 
 
-def test_pyproject_declares_no_project_table():
-    """A [project] table makes Vercel's Python builder prefer pyproject.toml
-    over requirements.txt. With no `dependencies` listed there, the build
-    installs nothing and the function cannot import fastapi."""
-    pyproject = (ROOT / "pyproject.toml").read_text()
-    has_project = any(line.strip() == "[project]" for line in pyproject.splitlines())
-    assert not has_project, (
-        "pyproject.toml declares [project]; either remove it so requirements.txt "
-        "is used, or list every runtime dependency under [project.dependencies]."
+def test_pyproject_is_kept_out_of_the_deployment_bundle():
+    """Vercel's Python builder runs `uv lock` against pyproject.toml whenever it
+    is present, and never reads requirements.txt.
+
+    With no [project] table the build fails outright:
+        error: No `project` table found in: /vercel/path0/pyproject.toml
+    With a [project] table that omits `dependencies`, it succeeds and installs
+    nothing — surfacing much later as ModuleNotFoundError at cold start.
+
+    So either keep the file out of the upload (what this repo does, since
+    pyproject.toml here holds only ruff and pytest config) or make it a complete
+    dependency manifest. The half-way state is the trap, and both halves of it
+    have already broken a deployment.
+    """
+    pathspec = pytest.importorskip("pathspec", reason="pathspec not installed")
+
+    spec = pathspec.PathSpec.from_lines("gitwildmatch", _vercelignore_lines())
+    declares_project = any(
+        line.strip() == "[project]" for line in (ROOT / "pyproject.toml").read_text().splitlines()
+    )
+
+    assert spec.match_file("pyproject.toml") or declares_project, (
+        "pyproject.toml is uploaded to Vercel but declares no [project] table — "
+        "`uv lock` will fail the build. Exclude it in .vercelignore, or give it a "
+        "[project] table listing every runtime dependency."
     )
 
 
@@ -103,12 +118,7 @@ def test_vercelignore_patterns_are_anchored():
 def test_nothing_the_runtime_imports_is_excluded_from_the_bundle():
     pathspec = pytest.importorskip("pathspec", reason="pathspec not installed")
 
-    lines = [
-        line
-        for raw in (ROOT / ".vercelignore").read_text().splitlines()
-        if (line := raw.strip()) and not line.startswith("#")
-    ]
-    spec = pathspec.PathSpec.from_lines("gitwildmatch", lines)
+    spec = pathspec.PathSpec.from_lines("gitwildmatch", _vercelignore_lines())
 
     tracked = subprocess.run(
         ["git", "ls-files"], cwd=ROOT, capture_output=True, text=True, check=True
@@ -119,8 +129,7 @@ def test_nothing_the_runtime_imports_is_excluded_from_the_bundle():
     required = [
         f
         for f in tracked
-        if f.startswith("app/")
-        or f in ("requirements.txt", "vercel.json", "pyproject.toml", ".python-version")
+        if f.startswith("app/") or f in ("requirements.txt", "vercel.json", ".python-version")
     ]
     excluded = [f for f in required if spec.match_file(f)]