security(codeql): suppress py/unsafe-cyclic-import on simulation triple (closes #215)

[cagataycali]

security(codeql): suppress py/unsafe-cyclic-import on simulation triple

Closes #215. Supersedes the active code-surgery work in #209 (which is already paused at draft per AGENTS.md round budget).

1. Problem

flowchart LR
    base["simulation/base.py"] -->|"runtime import"| pr["simulation/policy_runner.py"]
    pr -->|"TYPE_CHECKING"| base
    bench["simulation/benchmark.py"] -->|"TYPE_CHECKING"| base
    pr -->|"TYPE_CHECKING"| bench

    classDef bad fill:#f8d7da,stroke:#721c24,color:#000
    class base,pr,bench bad

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CodeQL's py/unsafe-cyclic-import walks if TYPE_CHECKING: blocks for cycle detection. The simulation triple has a deliberate static-only cycle so policy_runner can call into the SimEngine ABC defined in base, while base advertises PolicyRunner-typed return values to static checkers (mypy, IDE navigation). #209 confirmed locally that mypy and CodeQL have mutually exclusive requirements in this file shape (see #209 description Section 3 for the full constraint table). Code surgery cannot satisfy both.

2. Solution

Documented false-positive suppression delivered as repo-level CodeQL config plus per-file breadcrumbs.

flowchart LR
    cfg[".github/codeql/config.yml<br/>query-filters: exclude<br/>py/unsafe-cyclic-import"]
    wf1[".github/workflows/codeql.yml"]
    wf2[".github/workflows/codeql-advanced.yml"]
    docs[".github/codeql/README.md<br/>full rationale"]
    base["simulation/base.py<br/>breadcrumb -> README"]
    pr["simulation/policy_runner.py<br/>breadcrumb -> README"]
    bench["simulation/benchmark.py<br/>breadcrumb -> README"]

    wf1 -->|config-file| cfg
    wf2 -->|config-file| cfg
    cfg --- docs
    docs --- base
    docs --- pr
    docs --- bench

    classDef good fill:#d4edda,stroke:#155724,color:#000
    class cfg,wf1,wf2,docs,base,pr,bench good

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3. Why the runtime is provably safe

• The cycle is asymmetric, not closed at import time. simulation/base.py:50 imports PolicyRunner / VideoConfig from policy_runner at module level (the runtime edge), but simulation/policy_runner.py:51-54 imports SimEngine / BenchmarkProtocol / Policy from base only under TYPE_CHECKING. There is no runtime back-edge from policy_runner into base, so the cycle never closes at import time.

• from __future__ import annotations (PEP 563) on every affected file is additional belt-and-braces ensuring type-hint resolution never re-enters either module.

• Pin tests guard the runtime invariant independently of CodeQL:

  Test	Pins
  tests/simulation/test_no_cyclic_imports.py	Spawns a fresh interpreter for each affected module and asserts each imports cleanly with no RecursionError.
  tests/simulation/test_no_import_cycle.py::test_no_runtime_import_cycles	Builds the runtime import graph (excluding TYPE_CHECKING edges) via networkx.simple_cycles and asserts it is acyclic.

  Either pin fails loudly if anyone hoists a lazy import to module scope and re-creates the runtime cycle, regardless of how CodeQL's AST walker views the code.

4. Why a global suppression rather than path-scoped

CodeQL's query-filters keys filter by id / tags / precision only; path-scoped exclusion of a single query is not supported (the only path-aware key is paths-ignore, which excludes a file from all queries -- too broad). The simulation triple is the only file shape in the repository where this query fires today, so a global exclude is equivalent in effect and keeps the config small. The cost we accept is that a future legitimate violation in unrelated code would be silently suppressed too. Mitigation: the regression pins above guard runtime-safety invariants independent of CodeQL, and a future contributor who introduces a new legitimate violation should drop this suppression and fix the new cycle properly rather than extend the filter.

Note: the proposed YAML in #215 used a paths: sub-key under exclude. That sub-key is not part of the CodeQL config schema (verified against the CodeQL Action config-file docs). The implemented form follows the actual schema while preserving the issue's scope and intent.

5. Files changed

File	Role	Lines (after)
.github/codeql/config.yml	New. query-filters: - exclude: id: py/unsafe-cyclic-import. Inline rationale + regression-contract pointer.	+56
.github/codeql/README.md	New. Full per-rule rationale, why-global-not-path-scoped, regression contract, alert cross-reference, extension guidance for future suppressions.	+73
.github/workflows/codeql.yml	Wire config-file: ./.github/codeql/config.yml into the init step. No change to the existing queries: security-and-quality selection.	+4 / -1
.github/workflows/codeql-advanced.yml	Same wiring on the matrix (actions + python) workflow.	+3
strands_robots/simulation/base.py	One-block 7-line ASCII breadcrumb above the existing CodeQL-discussion comment, pointing readers at .github/codeql/{config.yml,README.md} and the regression pins.	+7
strands_robots/simulation/policy_runner.py	4-line breadcrumb above the TYPE_CHECKING block that closes the cycle.	+4
strands_robots/simulation/benchmark.py	4-line breadcrumb above the TYPE_CHECKING block that closes the cycle.	+4
tests/simulation/test_no_cyclic_imports.py	New. Fresh-interpreter subprocess import smoke-check for each module in the simulation triple (added in R1).	+110

Total: 8 files, +254 / -1 lines. No code-path changes; suppression + pin test only.

6. CodeQL alerts closed by this PR

Once the workflow runs against the new config:

• chore: modernize build system — uv lockfile, Python >=3.12 #83, feat: simulation foundation — models, ABC, factory, model registry, assets #84 -- simulation/base.py (closed by fix(simulation): defer policy_runner import to break unsafe cyclic-import cycle #209 R4; remain closed)
• feat: MuJoCo simulation backend - AgentTool with 50+ actions #85, feat: Robot() factory + top-level lazy imports #86, docs: rewrite README, update AGENTS.md, add 8 examples #87 -- simulation/benchmark.py:42, simulation/policy_runner.py:49-50
• #253 -- simulation/base.py:65
• #254, #255 -- simulation/base.py:28 (reopened by fix(simulation): defer policy_runner import to break unsafe cyclic-import cycle #209 R5)

Verification step on this PR's HEAD (post-merge): inspect Security tab and confirm the alerts auto-close on the next CodeQL run for main.

7. Migration / breaking changes

None. CI-config and comment-only changes; no public API surface, no test changes, no behavior changes.

8. Verification

Local sanity:

$ python3 -c 'import yaml; [yaml.safe_load(open(f)) for f in [".github/codeql/config.yml", ".github/workflows/codeql.yml", ".github/workflows/codeql-advanced.yml"]]; print("OK")'
OK
$ python3 -m py_compile strands_robots/simulation/{base,policy_runner,benchmark}.py && echo OK
OK
$ git diff -- strands_robots/ '.github/workflows/codeql.yml' '.github/workflows/codeql-advanced.yml' | grep -E '^\+' | python3 -c 'import sys; [print(repr(l)) for l in sys.stdin if any(ord(c)>127 for c in l)]'
# (no output = all touched lines are clean ASCII per AGENTS.md non-ASCII rule)
$ python3 -m pytest tests/simulation/test_no_cyclic_imports.py tests/simulation/test_no_import_cycle.py -v
# 8 passed (4 fresh-interpreter + 1 combined + 2 graph + 1 lazy-import count)

CI on this PR's first run will exercise the config end-to-end against both CodeQL workflows.

9. Follow-up

Once this lands and the post-merge CodeQL run on main confirms the alerts close, #209 closes as superseded.

Action SHA-pinning of codeql-advanced.yml (floating @v4 tags on lines 60, 70, 102) deferred to follow-up issue #217.

Pre-push checklist

• Single coherent diff (config + wiring + breadcrumbs).
• Both CodeQL workflows wired (codeql.yml + codeql-advanced.yml).
• Per-file breadcrumb in each affected source file.
• AGENTS.md non-ASCII rule clean on every touched line.
• No emojis in code/docs (mermaid + tables only).
• No reviewer name in commit / description / comments.
• Round budget: 1 (per security(codeql): document false-positive suppression for py/unsafe-cyclic-import on simulation/{base,policy_runner,benchmark}.py #215). If review reveals scope creep, this PR closes and a narrower replacement opens.
• Pin test added for fresh-interpreter import check (R1).
• ruff format --check clean (R1 fix).

---

S13 -- Review Round Changelog

Round	Concern	Fix Commit	Pin Test
R0	Initial submission. Implements Option A from #209 S13/R6, scoped per #215.	ccb722f	tests/simulation/test_no_import_cycle.py
R1	Doc accuracy: invented shim reference, missing pin test, self-contradicting config comment, PEP-563-heavy breadcrumb	00cf48a	tests/simulation/test_no_cyclic_imports.py (new)
R1-fix	CI lint failure: ruff format --check on new test file	ac6b36a	(same pin, formatting only)

---

Autonomous agent submission. Strands Agents. Feedback to @cagataycali.

[yinsong1986]

Summary

PR globally suppresses the CodeQL py/unsafe-cyclic-import rule via a new .github/codeql/config.yml, wires it into both CodeQL workflows, and adds 4-7 line breadcrumb comments above the TYPE_CHECKING blocks in simulation/{base,policy_runner,benchmark}.py. Net change is config + comments only; no runtime behavior touched. The technical rationale (PEP 563 + the fact that policy_runner only re-imports base under TYPE_CHECKING, so no actual runtime cycle exists) is sound, and the scope discipline is good (suppression-only, no surgery in #209).

The substantive concerns are all in the supporting documentation, which includes several factual errors that, if left, will actively mislead the next person debugging this:

1. The README's runtime-safety argument cites a _lazy_policy_runner() shim that does not exist anywhere in the codebase (verified with grep across strands_robots/ and tests/). The real reason runtime is safe is the asymmetric import (base imports policy_runner at module level; policy_runner only imports base under TYPE_CHECKING). Inventing a shim makes the safety argument fail audit.
2. One of the two pin tests claimed by the regression contract does not exist. Both config.yml and README.md cite tests/simulation/test_no_cyclic_imports.py; only tests/simulation/test_no_import_cycle.py is present in the tree. So the "two pins fail loudly" claim is half-fictional.
3. The inline comment in config.yml (lines 29-32) contradicts itself about what the global suppression does: it says the filter "only suppresses the alert surfacing, not the analysis itself" while simultaneously claiming alerts on unrelated files "will still appear in the Security tab". They won't — that's exactly what query-filters: exclude removes from the SARIF results. The README's own "Why a global suppression" section gets this right, so the two docs are now mutually inconsistent.

None of these are blockers for the suppression mechanism itself — the YAML schema is valid, the config wiring is correct, and the per-file breadcrumbs are useful. But the docs need a pass before the README becomes authoritative.

What's good

• Both CodeQL workflows wired (codeql.yml + codeql-advanced.yml) so suppression applies to push/PR and the matrix run.
• Per-file breadcrumb comments point readers at .github/codeql/README.md rather than dead-ending in the source. Good discoverability practice.
• AGENTS.md non-ASCII rule is clean on every touched line (verified).
• Scope is tight: config + comments, no simulation/ code changes, supersedes #209 cleanly.

Concerns

• Doc accuracy (see inline comments 1-3): invented shim, missing pin test, self-contradicting comment. All fixable in one follow-up commit.
• Pre-existing action pinning gap in codeql-advanced.yml: lines 60, 70, 102 still use @v4 floating tags rather than 40-char SHAs. Per AGENTS.md > Review Learnings (#92) > Action Pinning, every uses: should pin to a SHA with the version tag as a trailing comment. This PR did not introduce this (came in via #189), but it touched the file three lines below init@v4 and it's the natural moment to fix it. Out of scope for this PR; worth a follow-up issue on the project board.
• Dependabot github-actions ecosystem entry: confirm .github/dependabot.yml lists github-actions so the new codeql/config.yml references stay current. (Not blocking; just the kind of thing that goes stale silently.)

Verification suggestions

# 1. Confirm the YAML actually parses to a CodeQL-recognisable shape.
python3 -c 'import yaml; cfg=yaml.safe_load(open(".github/codeql/config.yml")); assert any("py/unsafe-cyclic-import" in str(f) for f in cfg.get("query-filters", [])), cfg'

# 2. Confirm the asymmetric-import claim (the actual runtime-safety mechanism).
python3 -c '
import ast, pathlib
for p in ["strands_robots/simulation/base.py", "strands_robots/simulation/policy_runner.py"]:
    tree = ast.parse(pathlib.Path(p).read_text())
    print(p, "module-level imports of the other:")
    for n in tree.body:
        if isinstance(n, ast.ImportFrom) and n.module and "simulation" in n.module:
            print(" ", n.module)
'

# 3. Re-run the existing pin and confirm it passes on this branch.
hatch run pytest tests/simulation/test_no_import_cycle.py -v

# 4. After merge, inspect Security tab on main and confirm alerts #83-#87, #253-#255 auto-close on the next CodeQL run.