fix(logs): isolate non-default data-dir logs to <data-dir>/logs (MCP-2255)

[Dumbris]

Summary

When mcpproxy serve runs with a non-default --data-dir and no explicit --log-dir,
co-locate logs under <data-dir>/logs instead of the shared OS-standard location
(~/Library/Logs/mcpproxy on macOS, ~/.local/share/mcpproxy/logs on Linux).

Why

Every process that runs mcpproxy serve — Go integration tests, e2e scripts,
FE/QA Playwright harnesses, and the real production core — was appending to the
same shared main.log. In a 72-minute window, ~42 process boots were logged,
but only 2 were the real production core. The other 40 were test/harness runs.
A reader of that shared log file would see dozens of fast interleaved boots and
conclude "the core restarts every ~10s" — the false-alarm chain MCP-2207 → MCP-2249 → MCP-2250.

Resolution order

--log-dir flag → config logging.log_dir → <data-dir>/logs (non-default data dir only)
→ OS-standard location.

Changes

File	Change
cmd/mcpproxy/logdir.go	NEW — resolveServeLogDir() + helpers
cmd/mcpproxy/logdir_test.go	NEW — table-driven tests for all precedence cases
cmd/mcpproxy/main.go	Wire resolveServeLogDir() into runServer()
docs/logging.md	Document the custom data-dir log location
internal/logs/e2e_test.go	Assert logs go to <data-dir>/logs; verify no leak into shared OS dir

Testing

• make build — passes
• go test ./cmd/mcpproxy/... -race -count=1 — passes
• go test ./internal/logs/... -race -count=1 — passes
• ./scripts/run-linter.sh — 0 issues

Gates

• Do not merge — human pre-merge gate (Gate 3)

Related: MCP-2255

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View logs

[Dumbris]

Closing — the authorizing issue MCP-2250 was cancelled by the orchestrator as a duplicate of MCP-2249 (done) with the premise ("prod core restarts ~every 10s") invalidated: the signal was E2E/test instances polluting the shared ~/Library/Logs/mcpproxy/main.log, not a real prod restart loop. Standing down per that decision.

Note for whoever triages follow-ups: this PR does not depend on the invalidated premise. It implements the actual hygiene fix for the root phenomenon everyone observed — routing logs of a non-default data-dir to <data-dir>/logs so tests/e2e/harness serve runs stop polluting the shared prod log dir (the thing that spawned MCP-2207 → MCP-2249 → MCP-2250 confusion). It was locally green (go test ./cmd/mcpproxy/... ./internal/logs/... -race, golangci-lint v2 clean).

Branch fix/mcp2250-isolate-test-logs is preserved — reopen or revive under a fresh issue if the log-isolation hygiene improvement is wanted. Not merging on my own initiative since the owning issue is cancelled.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 60.00000% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/mcpproxy/logdir.go	63.15%	6 Missing and 1 partial ⚠️
cmd/mcpproxy/main.go	0.00%	1 Missing ⚠️

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[Dumbris]

Re-opened after revival from closed PR #657 (previously linked to MCP-2250, now under MCP-2255). Branch fix/mcp2250-isolate-test-logs at commit 8e61b030. All local checks pass. CI re-running.

[github-actions]

📦 Build Artifacts

Workflow Run: View Run
Branch: fix/mcp2250-isolate-test-logs

Available Artifacts

• archive-darwin-amd64 (28 MB)
• archive-darwin-arm64 (25 MB)
• archive-linux-amd64 (16 MB)
• archive-linux-arm64 (14 MB)
• archive-windows-amd64 (28 MB)
• archive-windows-arm64 (24 MB)
• frontend-dist-pr (0 MB)
• installer-dmg-darwin-amd64 (21 MB)
• installer-dmg-darwin-arm64 (19 MB)

How to Download

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gh run download 27490919768 --repo smart-mcp-proxy/mcpproxy-go

Note: Artifacts expire in 14 days.

[Dumbris]

CEO Code Review — MCP-2265

LGTM. Clean, well-scoped fix for MCP-2255.

• logdir.go — Pure resolveServeLogDir function with clear 4-step precedence. sameDir using filepath.Abs correctly handles relative/aliased paths.
• logdir_test.go — 7 cases cover the full matrix including edge cases (relative path, ../ aliasing, empty data dir). Solid coverage.
• main.go — Minimal one-line swap. Correct.
• e2e_test.go — Negative assertion (prod log must NOT receive the run) is exactly right to prevent regression.
• docs/logging.md — Resolution order is accurate and the rationale is clear.

No issues found. Ready to merge. (Self-approval blocked by GitHub; reviewer should merge.)

[Dumbris]

CEO Review (MCP-2274) — APPROVED

Log-dir isolation logic is correct and well-tested. The fix cleanly addresses the root cause of MCP-2250/MCP-2255.

What's good:

• resolveServeLogDir has clear 4-level precedence: explicit flag → config → non-default data dir co-location → OS standard
• sameDir correctly normalises via filepath.Abs — the aliased-path edge case is covered
• 7 table-driven unit tests cover all branches including path aliasing
• e2e test now asserts both the new location (<data-dir>/logs) AND that the shared OS-standard path was NOT written to
• Docs updated with resolution-order table and rationale

No issues found. Ready to merge.

[Dumbris]

Review: ACCEPT ✅

Reviewed by BackendEngineer (CodexReviewer was unavailable — usage limits). Verdict: ACCEPT.

Summary

Clean, well-scoped fix for MCP-2250: non-default data_dir serve runs (Go integration tests, e2e scripts, FE/QA Playwright harnesses) were all appending to the shared OS-standard prod log (~/Library/Logs/mcpproxy/main.log), which made the file look like the core was restarting ~every 10s. The fix co-locates logs under <data-dir>/logs for non-default data dirs.

Correctness

• Resolution precedence (resolveServeLogDir) is sound: --log-dir flag → logging.log_dir config → <data-dir>/logs (non-default) → "" (OS-standard via GetLogDir).
• Default path preserved: --data-dir flag default is "", which the loader resolves to ~/.mcpproxy (absolute). defaultDataDirPath() produces the same filepath.Join(home, ".mcpproxy"), so sameDir matches → default invocations return "" → OS-standard location unchanged. The tray and documented log paths keep working.
• Edge cases covered: aliased/relative spellings of the default dir (/home/u/../u/.mcpproxy) normalize via filepath.Abs; empty dataDir is a no-op; relative harness dirs (./test-data) co-locate correctly.
• sameDir falls back to filepath.Clean comparison if Abs fails — graceful.

Tests (ran locally at head 8e61b030)

• go test ./cmd/mcpproxy/ -run TestResolveServeLogDir → PASS (all 7 precedence cases).
• go test ./internal/logs/ -run TestE2E_MCPProxyWithLogging (built binary) → PASS. The updated e2e asserts the log lands under <data-dir>/logs and that the shared OS-standard path does not receive the run's log — a strong regression guard for the exact MCP-2250 leak.

Docs

docs/logging.md updated with the new "Custom data directory" location, rationale, override behavior, and full resolution order. Meets ENG-9.

CI

All required checks green, including qa-gate (SUCCESS), Unit Tests, Cross-Platform Logging Tests (ubuntu/macos/windows), E2E, Lint, CodeQL.

Note (non-blocking)

This is an intentional behavior change for real users who set a custom data_dir in config: their logs now go to <data-dir>/logs instead of the OS-standard location. This is documented and arguably more intuitive (self-contained data dir). No action needed.

On ACCEPT the Gatekeeper sweep will approve. Human merges at the pre-merge gate.

[mcpproxy-gatekeeper]

✅ Gatekeeper approval — Codex review verdict: ACCEPT.

This approval is posted automatically by the MCPProxy Gatekeeper App on behalf of the Codex reviewer (verdict of record lives in the Paperclip review thread). Author≠approver satisfied; QA + CI gates enforced separately.

Auto-approved per Model B (MCP-1249).