chore(release): plugin.json version 0.22.1

Skip-Release: true

.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "skills",
   "description": "Mathias's engineering skills library, plus the hooks and MCP servers that make it enforceable: TDD, clean code, debugging, specs, discovery, CI, and secret hygiene.",
-  "version": "0.22.0",
+  "version": "0.22.1",
   "author": {
     "name": "Mathias",
     "url": "https://git.d-ma.be/mathias"

README.md

@@ -29,7 +29,7 @@ descriptions and "use when" triggers.
 /plugin install skills@mathias
 ```
 
-The plugin ships skills, the `secret-guard` + `pre-task-ritual` hooks, and the
+The plugin ships skills, the `secret-guard`, `mcp-destructive-guard` and `pre-task-ritual` hooks, and the
 brain/gitea/infra MCP servers as one versioned unit. Skills are namespaced
 (`skills:tdd`). Updates land when `.claude-plugin/plugin.json`'s `version`
 moves — CI bumps it on every release.

hooks/hooks.json

@@ -33,6 +33,16 @@
             "timeout": 5
           }
         ]
+      },
+      {
+        "matcher": "mcp__.*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "bash \"${CLAUDE_PLUGIN_ROOT}/hooks/mcp-destructive-guard.sh\"",
+            "timeout": 5
+          }
+        ]
       }
     ]
   }

hooks/mcp-destructive-guard.sh

@@ -0,0 +1,86 @@
+#!/usr/bin/env bash
+# PreToolUse hook (mcp__.* matcher) — makes a human approve irreversible MCP
+# verbs instead of letting the model run them unattended.
+#
+# Why (infra#508, infra ADR-0027): gitea-mcp authenticates by PAT pass-through,
+# so an agent holds the full scope of the caller's PAT. repo_delete's own guard
+# (confirm == repo) is filled in by the model on both sides: it stops typos,
+# not an injected or mistaken agent. The infra-mcp README claimed client-side
+# deny lists covered this; on 2026-10-01 none existed in any settings file.
+#
+# Policy: match gitea-mcp's verb spellings on ANY server name. The same tool is
+# reachable as mcp__plugin_skills_gitea__*, mcp__claude_ai_gitea__* or under
+# whatever name a host registers it with, so keying on the server name would
+# let a rename bypass the gate. It does NOT recognise other servers' spellings
+# of the same operation (e.g. a third-party `delete_repo`).
+#
+# file_write_branch is gated when it would land on main/master (on infra that
+# is a Flux deploy within ~60s — the same effect as pr_merge) or empty a file
+# (the same effect as file_delete). Writes to other branches pass.
+#
+# Emits "ask" or nothing; never "allow" (a hook allow would override the
+# user's own deny/ask rules). Always exits 0: Claude Code ignores a hook's
+# JSON on a non-zero exit. Anything it cannot parse — including a host
+# without jq — fails closed to "ask". The ask JSON is a literal, so the
+# fail-closed path needs no tool that might be missing.
+#
+# Scope limit, recorded in infra ADR-0027: this gates MCP calls only. A
+# session with the PAT in its environment can still reach the Gitea REST API
+# through a shell.
+
+set -u
+
+DESTRUCTIVE='repo_delete|file_delete|branch_delete|pr_merge|tbd_ship|repo_update|repo_mirror_push|workflow_run_trigger|tag_create|release_create'
+
+ask() {
+  # $1 must contain only [A-Za-z0-9 _.:()'/-] — it is spliced into JSON verbatim.
+  printf '{"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"ask","permissionDecisionReason":"%s"}}\n' "$1"
+  exit 0
+}
+
+INPUT="$(cat)"
+
+command -v jq >/dev/null 2>&1 \
+  || ask "mcp-destructive-guard: jq is not installed, so this MCP call cannot be checked. Approve only if you expected it."
+
+if ! TOOL_NAME="$(printf '%s' "$INPUT" | jq -er '.tool_name | strings | select(length > 0)' 2>/dev/null)"; then
+  ask "mcp-destructive-guard: could not read a tool name from this call, so it cannot be shown safe. Approve only if you expected it."
+fi
+
+case "$TOOL_NAME" in
+  mcp__*__*) ;;
+  *) exit 0 ;;
+esac
+
+verb="${TOOL_NAME##*__}"
+safe_verb="$(printf '%s' "$verb" | tr -cd 'A-Za-z0-9_-')"
+
+if printf '%s' "$verb" | grep -Eqix "($DESTRUCTIVE)"; then
+  ask "Irreversible MCP verb '$safe_verb' (infra ADR-0027): needs your approval. The model filled in every argument, including any confirm field."
+fi
+
+if printf '%s' "$verb" | grep -Eqix 'file_write_branch'; then
+  # Cleared only when there is exactly ONE key that case-folds to "branch" and
+  # one to "content": gitea-mcp decodes with Go encoding/json, which matches
+  # keys case-insensitively and lets the last one win, so {"branch":"feat/x",
+  # "Branch":"main"} landed on main while a lowercase-only read saw feat/x.
+  # The branch is cleared by SHAPE (allowlist), not by a blocklist of names:
+  # "refs/heads/main" created a second ref that wedged API writes to main.
+  verdict="$(printf '%s' "$INPUT" | jq -r '
+      .tool_input as $i
+      | if ($i | type) != "object" then "ask" else
+          ([$i | to_entries[] | select(.key | ascii_downcase == "branch")]) as $b
+          | ([$i | to_entries[] | select(.key | ascii_downcase == "content")]) as $c
+          | if ($b | length) != 1 or ($c | length) != 1 then "ask"
+            elif ($b[0].key != "branch") or ($c[0].key != "content") then "ask"
+            elif ($b[0].value | type) != "string" or ($c[0].value | type) != "string" then "ask"
+            elif ($b[0].value | test("^[A-Za-z0-9][A-Za-z0-9._/-]*$") | not) then "ask"
+            elif ($b[0].value | test("\\.\\.|^refs/|/$")) then "ask"
+            elif ($b[0].value | ascii_downcase | . == "main" or . == "master") then "ask"
+            elif ($c[0].value | test("^\\s*$")) then "ask"
+            else "pass" end
+        end' 2>/dev/null || echo ask)"
+  [ "$verdict" = "pass" ] \
+    || ask "file_write_branch to main/master, an unusual branch name, or emptying a file (infra ADR-0027): needs your approval."
+fi
+exit 0

tests/mcp_destructive_guard_test.sh

@@ -0,0 +1,118 @@
+#!/bin/sh
+# Tests for hooks/mcp-destructive-guard.sh — the PreToolUse gate that makes a
+# human approve irreversible MCP verbs (infra#508, infra ADR-0027).
+#
+# Contract: reads PreToolUse hook JSON on stdin, ALWAYS exits 0, and answers
+# in hookSpecificOutput.permissionDecision. "ask" = a human must approve;
+# empty stdout ("NONE") = no opinion, normal permission rules apply. The guard
+# never emits "allow": an allow from a hook would bypass the user's own rules.
+#
+# Cases marked (gatekeeper) are escapes found by the skills#52 review: each
+# passed the first version of this suite.
+
+set -u
+
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)
+GUARD="$ROOT/hooks/mcp-destructive-guard.sh"
+
+pass=0
+fail=0
+
+# run_guard <json> [PATH] — invoked exactly as hooks.json does: `bash <path>`.
+# Prints "<decision> rc=<exit>", decision NONE for an empty answer.
+run_guard() {
+  if [ $# -ge 2 ]; then
+    _out=$(printf '%s' "$1" | PATH="$2" "$BASH_BIN" "$GUARD"); _rc=$?
+  else
+    _out=$(printf '%s' "$1" | bash "$GUARD"); _rc=$?
+  fi
+  if [ -z "$_out" ]; then _d=NONE
+  else _d=$(printf '%s' "$_out" | jq -r '.hookSpecificOutput.permissionDecision // "NONE"' 2>/dev/null || echo BROKEN)
+  fi
+  printf '%s rc=%s' "$_d" "$_rc"
+}
+BASH_BIN=$(command -v bash)
+
+check() {
+  _want=$1 _json=$2 _label=$3
+  _got=$(run_guard "$_json")
+  if [ "$_got" = "$_want rc=0" ]; then
+    pass=$((pass + 1)); printf '  ok   %s\n' "$_label"
+  else
+    fail=$((fail + 1)); printf '  FAIL %s\n       want=%s rc=0 got=%s\n       in=%s\n' "$_label" "$_want" "$_got" "$_json"
+  fi
+}
+tool() { printf '{"tool_name":"%s","tool_input":{"owner":"mathias","repo":"x"}}' "$1"; }
+
+echo "mcp-destructive-guard tests"
+
+for v in repo_delete file_delete branch_delete pr_merge tbd_ship repo_update repo_mirror_push \
+         workflow_run_trigger tag_create release_create; do
+  check ask "$(tool "mcp__plugin_skills_gitea__$v")" "plugin gitea $v asks"
+done
+
+# The verb is matched on any server name: connector, bare, or renamed.
+check ask "$(tool mcp__claude_ai_gitea__repo_delete)" "connector namespace asks"
+check ask "$(tool mcp__gitea__repo_delete)"           "bare server name asks"
+check ask "$(tool mcp__git__repo_delete)"             "renamed server still asks"
+check ask "$(tool mcp__plugin_skills_gitea__REPO_DELETE)" "uppercase verb asks"
+# The verb is the LAST segment (gatekeeper: parsing the second segment stayed green).
+check ask  "$(tool mcp__a__b__repo_delete)" "verb taken from last segment"
+check NONE "$(tool mcp__repo_delete__issue_get)" "server named like a verb does not trigger"
+
+# file_write_branch: content landing on main, or emptying a file, is the same
+# effect as the gated pr_merge / file_delete (gatekeeper).
+fwb() { printf '{"tool_name":"mcp__plugin_skills_gitea__file_write_branch","tool_input":{"branch":"%s","content":"%s"}}' "$1" "$2"; }
+check ask  "$(fwb main x)"     "file_write_branch to main asks"
+check ask  "$(fwb master x)"   "file_write_branch to master asks"
+check ask  "$(fwb feat/y '')"  "file_write_branch emptying a file asks"
+check ask  '{"tool_name":"mcp__plugin_skills_gitea__file_write_branch","tool_input":{"content":"x"}}' "file_write_branch without branch asks"
+check NONE "$(fwb feat/y x)"   "file_write_branch to a feature branch passes"
+
+# Go's encoding/json matches keys case-insensitively, last one wins: gitea-mcp
+# wrote to main from {"branch":"feat/y8","Branch":"main"} while the hook read
+# only `branch` (gatekeeper round 2, verified against a real Gitea). So the
+# guard clears a write only when exactly one key case-folds to branch/content.
+FWB=mcp__plugin_skills_gitea__file_write_branch
+check ask  "{\"tool_name\":\"$FWB\",\"tool_input\":{\"branch\":\"feat/y8\",\"Branch\":\"main\",\"content\":\"x\"}}" "case-variant Branch key asks"
+check ask  "{\"tool_name\":\"$FWB\",\"tool_input\":{\"branch\":\"feat/y\",\"content\":\"x\",\"Content\":\"\"}}" "case-variant Content key asks"
+check ask  "{\"tool_name\":\"$FWB\",\"tool_input\":{\"BRANCH\":\"feat/y\",\"content\":\"x\"}}" "only an uppercase BRANCH key asks"
+check ask  "$(fwb Main x)"  "file_write_branch to Main asks"
+check ask  "{\"tool_name\":\"$FWB\",\"tool_input\":{\"branch\":\"feat/y\"}}" "missing content key asks"
+check ask  "$(fwb feat/y ' ')" "whitespace-only content asks"
+check ask  "{\"tool_name\":\"$FWB\",\"tool_input\":\"branch=feat/y\"}" "non-object tool_input asks"
+# Branch names are cleared by shape, not by blocklist: refs/heads/main created a
+# second ref that wedged every API write to main (gatekeeper side finding).
+check ask  "$(fwb refs/heads/main x)" "refs/ prefixed branch asks"
+check ask  "$(fwb ' main' x)"         "branch with whitespace asks"
+check ask  "$(fwb '../main' x)"       "branch with .. asks"
+check NONE "$(fwb release/v1.2_x x)"  "ordinary branch name passes"
+
+# Reversible / read verbs pass through.
+for v in issue_close issue_create file_read repo_list pr_create; do
+  check NONE "$(tool "mcp__plugin_skills_gitea__$v")" "$v passes through"
+done
+check NONE "$(tool mcp__plugin_skills_gitea__repo_delete_dry_run_list)" "suffix near-miss passes"
+check NONE "$(tool Bash)" "non-MCP tool passes"
+check NONE "$(tool repo_delete)" "non-MCP tool named like a verb passes"
+
+# Malformed input fails CLOSED (gatekeeper: non-string tool_name got NONE).
+check ask 'not json'                        "non-JSON asks"
+check ask '{}'                              "missing tool_name asks"
+check ask '{"tool_name":null}'              "null tool_name asks"
+check ask '{"tool_name":""}'                "empty tool_name asks"
+check ask '{"tool_name":5}'                 "number tool_name asks"
+check ask '{"tool_name":["mcp__x__repo_delete"]}' "array tool_name asks"
+check ask '{"tool_name":{"a":1}}'           "object tool_name asks"
+
+# Without jq on PATH the guard must still answer ask, not stay silent
+# (gatekeeper: the fail-closed path itself needed jq).
+nojq=$(mktemp -d); trap 'rm -rf "$nojq"' EXIT
+for b in bash cat grep tr sed; do ln -s "$(command -v $b)" "$nojq/$b"; done
+_got=$(run_guard "$(tool mcp__plugin_skills_gitea__repo_delete)" "$nojq")
+if [ "$_got" = "ask rc=0" ]; then pass=$((pass+1)); echo "  ok   no jq on PATH still asks"; else fail=$((fail+1)); echo "  FAIL no jq on PATH: got=$_got"; fi
+_got=$(run_guard "$(tool mcp__plugin_skills_gitea__issue_get)" "$nojq")
+if [ "$_got" = "ask rc=0" ]; then pass=$((pass+1)); echo "  ok   no jq on PATH asks even for a read verb (cannot parse = cannot clear)"; else fail=$((fail+1)); echo "  FAIL no jq read verb: got=$_got"; fi
+
+printf '\n%d passed, %d failed\n' "$pass" "$fail"
+[ "$fail" -eq 0 ]