refactor(server): move DLC path resolution to lib/dlc_paths.py (R3 substrate)

[byrongamatos]

The keystone for the path-dependent routers (ws_highway @ 902 lines, song, audio-local-path, sloppak): the "where do the song files live + safe containment" layer leaves server.py so a router can reach it.

What moves

• _resolve_dlc_path (pure — takes dlc + filename, no globals) → verbatim.
• _get_dlc_dir reads the env-derived paths through the appstate seam (appstate.dlc_dir / dlc_dir_env / config_dir) instead of module globals, so lib/dlc_paths.py does no import-time IO.
• appstate gains dlc_dir / dlc_dir_env slots (config_dir already there); server.py configures them. All three are env-derived, so a setenv+reimport fixture reconfigures them for free — zero setattr retargeting.

Zero test churn, via re-export

server.py re-exports both (from dlc_paths import _get_dlc_dir, _resolve_dlc_path), so its 24+16 call sites and the tests that reach server._get_dlc_dir() / server._resolve_dlc_path() directly (test_dlc_junction, test_highway_ws_notation, test_highway_ws_authors) resolve unchanged. No test edits.

server.py: 9,085 → 9,008.

Verification

• _resolve_dlc_path byte-identical to origin/main; _get_dlc_dir's only change is the three path identifiers → appstate.*.
• Route table identical (143); pyflakes clean; packaging guard 52 (picked up dlc_paths); pytest 2407 passed (the three direct-caller suites green through the re-export); npm run lint 0.
• Boot smoke: library scans (8 songs — exercises _get_dlc_dir), a real song resolves and serves art (_resolve_dlc_path), and the highway WS reaches ready with notes.
• Codex: 0 findings.

Next: ws_highway (902 lines) now needs only STATIC_DIR/SLOPPAK_CACHE_DIR in the seam (+ retargeting their ~5 setattr sites) and its few remaining helpers, then it can move.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved DLC library path handling across configuration and environment settings.
  • Added stronger validation to prevent invalid or unsafe DLC file paths.
  • Preserved support for valid library locations, including linked or mounted directories.

• Documentation

  • Updated release notes with the latest router extraction and DLC path handling details.
  • Updated size-exemption documentation with the current server line count.

[coderabbitai]

📝 Walkthrough

Walkthrough

DLC directory selection and path containment validation moved from server.py into lib/dlc_paths.py. appstate now carries DLC configuration values, and server.py wires the extracted functions through that seam. Changelog and size-exemption documentation were updated.

Changes

DLC path resolution

Layer / File(s)	Summary
DLC configuration and path validation lib/appstate.py, lib/dlc_paths.py	Adds dlc_dir and dlc_dir_env appstate slots, resolves DLC directories from environment or configuration, and validates filenames against the DLC root.
Server integration and release metadata server.py, CHANGELOG.md, docs/size-exemptions.md	Routes DLC values through appstate, imports the extracted resolvers, removes their duplicate server implementations, and updates related documentation.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• got-feedBack/feedBack#833: Uses the same appstate router-seam pattern for shared configuration and singleton values.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 60.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	Accurately describes the main change: moving DLC path resolution into lib/dlc_paths.py from server.py.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/r3-dlc-paths

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[coderabbitai]

🧹 Nitpick comments (1)

lib/dlc_paths.py (1)

26-39: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Consider logging the swallowed config-parse error.

The blind except Exception: pass (ruff S110/BLE001) silently discards a malformed config.json, so a user misconfiguration surfaces only as a mysterious "DLC folder not configured". A debug/warning log would make this diagnosable without changing the fallback behavior.

♻️ Log instead of silently passing

         if config_file.exists():
             try:
                 cfg = json.loads(config_file.read_text(encoding="utf-8"))
-            except Exception:
-                pass
+            except Exception:
+                logging.warning("Ignoring unreadable/invalid %s", config_file, exc_info=True)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/dlc_paths.py` around lines 26 - 39, Replace the silent `except Exception:
pass` in the config-loading logic with a warning or debug log that includes the
parsing exception and identifies `config.json`, while preserving the existing
fallback behavior of continuing with `cfg` unset.

Source: Linters/SAST tools

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@lib/dlc_paths.py`:
- Around line 26-39: Replace the silent `except Exception: pass` in the
config-loading logic with a warning or debug log that includes the parsing
exception and identifies `config.json`, while preserving the existing fallback
behavior of continuing with `cfg` unset.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: e1593759-5ee7-43b9-a199-a61e9cfdb601

📥 Commits

Reviewing files that changed from the base of the PR and between 6da01c5 and 72c01c3.

📒 Files selected for processing (5)

• CHANGELOG.md
• docs/size-exemptions.md
• lib/appstate.py
• lib/dlc_paths.py
• server.py