Clarify need to include pyproject.toml with --no-install-project (#6581)

## Summary

See: https://github.com/astral-sh/uv/issues/6573

crates/uv/tests/sync.rs

@@ -861,6 +861,18 @@ fn no_install_project() -> Result<()> {
      + sniffio==1.3.1
     "###);
 
+    // However, we do require the `pyproject.toml`.
+    fs_err::remove_file(pyproject_toml)?;
+
+    uv_snapshot!(context.filters(), context.sync().arg("--no-install-project"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: No `pyproject.toml` found in current directory or any parent directory
+    "###);
+
     Ok(())
 }
 
@@ -928,6 +940,18 @@ fn no_install_workspace() -> Result<()> {
      + sniffio==1.3.1
     "###);
 
+    // However, we do require the `pyproject.toml`.
+    fs_err::remove_file(child.join("pyproject.toml"))?;
+
+    uv_snapshot!(context.filters(), context.sync().arg("--no-install-workspace"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Workspace member `[TEMP_DIR]/child` is missing a `pyproject.toml` (matches: `child`)
+    "###);
+
     Ok(())
 }
 

docs/guides/integration/docker.md

@@ -228,8 +228,9 @@ a big time saver.
 FROM python:3.12-slim
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /bin/uv
 
-# Copy the lockfile into the image
+# Copy the lockfile and `pyproject.toml` into the image
 ADD uv.lock /app/uv.lock
+ADD pyproject.toml /app/pyproject.toml
 
 # Install dependencies
 WORKDIR /app
@@ -243,6 +244,9 @@ WORKDIR /app
 RUN uv sync --frozen
 ```
 
+Note that the `pyproject.toml` is required to identify the project root and name, but the project
+_contents_ are not copied into the image until the final `uv sync` command.
+
 !!! tip
 
     If you're using a [workspace](../../concepts/workspaces.md), then use the