refactor(lambdagent): migrate to src-layout (mirror GitHub upstream)

Mirrors commits 76edf32 + 2f360a4 from kenny67nju/lambdagent on GitHub.
Every package file under lambdagent/ moved into lambdagent/src/lambdagent/.
Public import paths are unchanged (from lambdagent.X import Y still works).

Monorepo consumers patched to keep working:
  - tests/conftest.py: prepend lambdagent/src in addition to monorepo
    root, with explanatory docstring.
  - agentexample/qaagent67/scripts/analyze_results.py: add
    /home/67/lambdagentpaas/lambdagent/src to sys.path.
  - agentexample/qaagent67/scripts/run_comparison.py: same.

setup.sh and Dockerfile already use 'pip install -e ./lambdagent', which
remains a no-op change — setuptools.packages.find { where = ['src'] } +
package-dir = {'' = 'src'} discovers everything correctly.

Local: 95 passed / 3 pre-existing failures (unrelated to layout).

agentexample/qaagent67/scripts/analyze_results.py

@@ -9,6 +9,9 @@ from pathlib import Path
 
 sys.path.insert(0, '/home/67/knowledge/maritime')
 sys.path.insert(0, '/home/67/lambdagentpaas')
+# lambdagent migrated to src-layout — add the src dir so 'from lambdagent.X'
+# still resolves when running outside an editable-install venv.
+sys.path.insert(0, '/home/67/lambdagentpaas/lambdagent/src')
 
 RESULTS_FILE = Path('/home/67/knowledge/maritime/batch_results_200.json')
 REPORT_FILE = Path('/home/67/knowledge/maritime/analysis_report.md')

agentexample/qaagent67/scripts/run_comparison.py

@@ -8,6 +8,9 @@ import time
 import sys
 sys.path.insert(0, '/home/67/knowledge/maritime')
 sys.path.insert(0, '/home/67/lambdagentpaas')
+# lambdagent migrated to src-layout — add the src dir so 'from lambdagent.X'
+# still resolves when running outside an editable-install venv.
+sys.path.insert(0, '/home/67/lambdagentpaas/lambdagent/src')
 
 from search_engine import search
 from lambdagent.providers import create_provider

lambdagent/CHANGELOG.md

@@ -5,6 +5,9 @@ Format inspired by [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+### Changed (structural)
+- **Migrated from flat layout to src-layout** (PyPA recommended). All package code now lives under `src/lambdagent/` instead of at the repo root. Public API and import paths are 100% unchanged — every `from lambdagent.X import Y` keeps working identically. This removes three previous workarounds (`conftest.py collect_ignore`, `tool.setuptools.package-dir`, explicit `packages = [...]` list) and eliminates the fragility where the repo's parent-directory name could break pytest. The `--import-mode=importlib` pytest workaround is also no longer needed.
+
 ### Fixed
 - **`pip install -e .` is now unblocked.** `pyproject.toml::project.license` migrated from the deprecated `{text = "BUSL-1.1"}` dict form to the SPDX string form (`"BUSL-1.1"`) required by setuptools ≥ 77.
 - **Stop shadowing stdlib `types` and `trace`.** Renamed top-level `types.py → lam_types.py` and `trace.py → tracing.py`. All public symbols (`LamType`, `T_STR`, `TraceStore`, …) are re-exported unchanged from `lambdagent`; only direct sub-module imports need updating.
@@ -18,8 +21,7 @@ Format inspired by [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - `CONTRIBUTING.md` with setup, workflow, and PR expectations.
 - `CODE_OF_CONDUCT.md` (Contributor Covenant 2.1).
 - GitHub Actions CI: pytest matrix on Python 3.10 / 3.11 / 3.12.
-- `conftest.py` at repo root for flat-layout test discovery.
-- `[tool.pytest.ini_options]` block: `importlib` import mode, deprecation-warning filters.
+- `[tool.pytest.ini_options]` block with deprecation-warning filters.
 
 ### Changed
 - `providers.ClaudeLam` is **deprecated** (DeprecationWarning, removed in 0.3.0). Use `lambdagent.Lam(provider=ClaudeCodeProvider(...))` instead.

lambdagent/README.md

@@ -255,7 +255,14 @@ python examples/nl2agent_demo.py "Build a research assistant that can search and
 ## Architecture
 
 ```
-lambdagent/                  # ~35,000 lines, 125 .py files, 152 exported symbols
+lambdagent/                  # repo root — src-layout per PyPA recommendation
+├── pyproject.toml           # setuptools.packages.find finds src/lambdagent
+├── README.md / LICENSE / CHANGELOG.md / SECURITY.md / CONTRIBUTING.md / ...
+├── examples/                # standalone examples
+├── tests/                   # pytest suite (519 tests, 9-OS×Python matrix)
+├── .github/workflows/       # tests / codeql / release
+│
+└── src/lambdagent/          # ~35,000 lines, 125 .py files, 152 exported symbols
 │
 │   ── Core λ-calculus ─────────────────────────────────────────────
 ├── __init__.py              # Public API — 152 symbols

lambdagent/pyproject.toml

@@ -103,25 +103,17 @@ Issues = "https://github.com/kenny67nju/lambdagent/issues"
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
-addopts = "--import-mode=importlib"
 filterwarnings = [
     "ignore::DeprecationWarning:lambdagent.from_config",
     "ignore::DeprecationWarning:lambdagent.lint",
 ]
 
 [tool.setuptools]
-package-dir = {"lambdagent" = "."}
-packages = [
-    "lambdagent",
-    "lambdagent.agentruntime",
-    "lambdagent.builtin_tools",
-    "lambdagent.cli",
-    "lambdagent.extractors",
-    "lambdagent.fromconfig",
-    "lambdagent.providers",
-    "lambdagent.skillpacks",
-    "lambdagent.skillpacks.research",
-]
+package-dir = {"" = "src"}
+
+[tool.setuptools.packages.find]
+where = ["src"]
+include = ["lambdagent*"]
 
 [tool.setuptools.package-data]
 lambdagent = ["py.typed"]