Initial scaffolding: module, directory structure, Makefile, linter config

.golangci.yaml

@@ -0,0 +1,122 @@
+# golangci-lint v2 configuration for mcr.
+# Principle: fail loudly. Security and correctness issues are errors, not warnings.
+
+version: "2"
+
+run:
+  timeout: 5m
+  # Include test files so security rules apply to test helpers too.
+  tests: true
+
+linters:
+  default: none
+  enable:
+    # --- Correctness ---
+    # Unhandled errors are silent failures; in auth code they become vulnerabilities.
+    - errcheck
+    # go vet: catches printf-verb mismatches, unreachable code, suspicious constructs.
+    - govet
+    # Detects assignments whose result is never used; dead writes hide logic bugs.
+    - ineffassign
+    # Detects variables and functions that are never used.
+    - unused
+
+    # --- Error handling ---
+    # Enforces proper error wrapping (errors.Is/As instead of == comparisons) and
+    # prevents accidental discard of wrapped sentinel errors.
+    - errorlint
+
+    # --- Security ---
+    # Primary security scanner: hardcoded secrets, weak RNG, insecure crypto
+    # (MD5/SHA1/DES/RC4), SQL injection, insecure TLS, file permission issues, etc.
+    - gosec
+    # Deep static analysis: deprecated APIs, incorrect mutex use, unreachable code,
+    # incorrect string conversions, simplification suggestions, and hundreds of other checks.
+    - staticcheck
+
+    # --- Style / conventions ---
+    # Enforces Go naming conventions and selected style rules.
+    - revive
+
+  settings:
+    errcheck:
+      # Do NOT flag blank-identifier assignments: `_ = rows.Close()` in defers,
+      # `_ = tx.Rollback()` after errors, and `_ = fs.Parse(args)` with ExitOnError
+      # are all legitimate patterns where the error is genuinely unrecoverable or
+      # irrelevant. The default errcheck (without check-blank) still catches
+      # unchecked returns that have no assignment at all.
+      check-blank: false
+      # Flag discarded ok-value in type assertions: `c, _ := x.(*T)` — the ok
+      # value should be checked so a failed assertion is not silently treated as nil.
+      check-type-assertions: true
+
+    govet:
+      # Enable all analyzers except shadow. The shadow analyzer flags the idiomatic
+      # `if err := f(); err != nil { ... }` pattern as shadowing an outer `err`,
+      # which is ubiquitous in Go and does not pose a security risk in this codebase.
+      enable-all: true
+      disable:
+        - shadow
+
+    gosec:
+      # Treat all gosec findings as errors, not warnings.
+      severity: medium
+      confidence: medium
+      excludes:
+        # G104 (errors unhandled) overlaps with errcheck; let errcheck own this.
+        - G104
+
+    errorlint:
+      errorf: true
+      asserts: true
+      comparison: true
+
+    revive:
+      rules:
+        # error-return and unexported-return are correctness/API-safety rules.
+        - name: error-return
+          severity: error
+        - name: unexported-return
+          severity: error
+        # Style rules.
+        - name: error-strings
+          severity: warning
+        - name: if-return
+          severity: warning
+        - name: increment-decrement
+          severity: warning
+        - name: var-naming
+          severity: warning
+        - name: range
+          severity: warning
+        - name: time-naming
+          severity: warning
+        - name: indent-error-flow
+          severity: warning
+        - name: early-return
+          severity: warning
+        # exported and package-comments are omitted: this is a personal project,
+        # not a public library; godoc completeness is not a CI requirement.
+
+formatters:
+  enable:
+    # Enforces gofmt formatting. Non-formatted code is a CI failure.
+    - gofmt
+    # Manages import grouping and formatting; catches stray debug imports.
+    - goimports
+
+issues:
+  # Do not cap the number of reported issues; in security code every finding matters.
+  max-issues-per-linter: 0
+  max-same-issues: 0
+
+  exclusions:
+    paths:
+      - vendor
+    rules:
+      # In test files, allow hardcoded test credentials (gosec G101) since they are
+      # intentional fixtures, not production secrets.
+      - path: "_test\\.go"
+        linters:
+          - gosec
+        text: "G101"