Update the canonical .golangci.yml for golangci-lint v2.15.0 (closes #142)

Moves the pin to v2.15.0 and enables canonicalheader again, because that
release fixes the random misses behind
#105.

The depguard exemption reached every directory below one ending in test,
and a whole checkout under such a directory. It now covers only the files
directly inside. gomodguard_v2 also blocks github.com/go-redis/redis/v9,
whose pre-releases can still be imported.

Three comments are corrected. A new comment says the file has no
formatters section, so golangci-lint run checks no formatting.

Model: opus-5-5

.golangci.yml

@@ -3,6 +3,9 @@ version: "2"
 # Config schema uses the golangci-lint v2 layout (settings live under
 # linters.settings, not top-level linters-settings) so that the
 # thresholds below are actually applied by golangci-lint >= v2.
+#
+# This file has no formatters section, so golangci-lint run checks no
+# formatting. A repository's script/fmt-check checks it, on the host.
 
 run:
   timeout: 5m
@@ -16,13 +19,13 @@ linters:
     - gomodguard_v2
   disable:
     # Genuinely incompatible with project patterns
-    - exhaustruct      # Requires all struct fields
-    - exhaustruct_v5   # Requires all struct fields (successor to exhaustruct)
+    - exhaustruct_v5   # Requires all struct fields
     - godot            # Requires comments to end with periods
     - wrapcheck        # Too verbose for internal packages
     - varnamelen       # Short names like db, id are idiomatic Go
     # Deprecated: the warning is attached to the old name, so it is
     # silenced by disabling that name, not by enabling the successor.
+    - exhaustruct      # Deprecated, replaced by exhaustruct_v5
     - wsl              # Deprecated, replaced by wsl_v5
     - gomodguard       # Deprecated, replaced by gomodguard_v2
   settings:
@@ -40,7 +43,8 @@ linters:
       # test-support package exists to hand a test privileges the program
       # itself must never have, so a file that is not a test must not import
       # one. Test files, and the files inside a package whose directory name
-      # ends in `test`, are where that code belongs, and are exempt.
+      # ends in `test`, are where that code belongs, and are exempt. A package
+      # in a subdirectory of that directory is not exempt.
       #
       # The deny list below is the one part of this file a repository is
       # expected to extend, and the only part it may. depguard matches an
@@ -55,14 +59,14 @@ linters:
           files:
             - "$all"
             - "!$test"
-            - "!**/*test/**"
+            - "!**/*test/*"
           deny:
             - pkg: net/http/httptest
               desc: >-
                 Test-support code belongs in test files and in packages whose
                 directory name ends in test, not in the shipped binary.
-    # Only decisions already recorded in the Go package defaults are
-    # listed here. Every entry matches the module path exactly.
+    # Each entry names a module not to use and what to use instead. Every
+    # entry matches the module path exactly.
     gomodguard_v2:
       blocked:
         - module: github.com/rs/zerolog
@@ -71,7 +75,7 @@ linters:
           reason: "Structured logging is stdlib log/slog."
         # One entry per pre-fork module path, because the later releases
         # are separate paths. A prefix match would be shorter but would
-        # also reach github.com/go-redis/redismock, the test double for
+        # also reach github.com/go-redis/redismock/v9, the test double for
         # the successor these entries recommend.
         - module: github.com/go-redis/redis
           recommendations:
@@ -85,6 +89,10 @@ linters:
           recommendations:
             - github.com/redis/go-redis/v9
           reason: "Pre-fork module; use the maintained go-redis v9."
+        - module: github.com/go-redis/redis/v9
+          recommendations:
+            - github.com/redis/go-redis/v9
+          reason: "Pre-fork module; use the maintained go-redis v9."
         - module: github.com/sergi/go-diff
           recommendations:
             - github.com/aymanbagabas/go-udiff

TODO.md

@@ -21,15 +21,23 @@ fmt-check, and commit.
 
 # Completed Steps
 
-- 2026-11-01: Moved the canonical golangci-lint to v2.15.0 (released
-  2026-10-16), still built with go1.27.0, so the `go` directive rule is
-  unchanged. The canonical `.golangci.yml` passes `golangci-lint config verify`
-  on v2.15.0, and `default: all` switches on no new linter. `canonicalheader` is
-  enabled again (issue 105): v2.15.0 carries the upstream commit "fix:
-  non-deterministic results", and on a scratch package with two planted findings
-  beside a `ResponseWriter.Header()` call, linted 20 times with each pinned
-  image, v2.14.0 reported them on 8 runs and nothing on 12, while v2.15.0
-  reported them on all 20.
+- 2026-11-03: The canonical golangci-lint is now v2.15.0, still built with
+  go1.27.0, so the `go` directive rule is unchanged (issue 142). Repositories
+  pick this up on their next re-vendor. Each item in the canonical
+  `.golangci.yml` was tried on a scratch module. These changed:
+    - `canonicalheader` is enabled again, because v2.15.0 fixes the random
+      misses behind issue 105.
+    - The `depguard` exemption covers only the files directly inside a directory
+      whose name ends in `test`. It used to reach every directory below that one
+      too.
+    - `gomodguard_v2` also blocks `github.com/go-redis/redis/v9`, whose
+      pre-releases can still be imported under that path.
+    - Three comments now say what is true: `exhaustruct` is listed as
+      deprecated, the test double is named `github.com/go-redis/redismock/v9`,
+      and the claim that every blocked module is in the Go package defaults is
+      gone.
+    - A comment says the file has no `formatters` section, so
+      `golangci-lint run` checks no formatting.
 - 2026-10-27: Added `prompts/API_POLICIES.md`
   (https://git.eeqj.de/sneak/prompts/issues/137). It holds sneak's rule from
   https://git.eeqj.de/sneak/routewatch/issues/199 that a value in an API

prompts/REPO_POLICIES.md

@@ -1,6 +1,6 @@
 ---
 title: Repository Policies
-last_modified: 2026-11-01
+last_modified: 2026-11-03
 ---
 
 This document covers repository structure, tooling, and workflow standards. Code