Allow CAPABILITY_UNSAFE_POINTER in baseline

Go 1.26 changes how capslock traces through stdlib internals
(reflect, encoding/json), causing it to report UNSAFE_POINTER for
any package that uses reflection. This is a transitive artifact —
go-toml does not import "unsafe" directly. Include it in the
baseline so the check passes on both Go 1.24 and 1.26, and remove
it from FORBIDDEN_CAPS.

https://claude.ai/code/session_01HwDXpKevFLhE5EfrR6JrBn

.github/workflows/capabilities.yml

@@ -0,0 +1,25 @@
+name: capabilities
+on:
+  push:
+    branches:
+      - v2
+  pull_request:
+    branches:
+      - v2
+
+jobs:
+  check:
+    name: check capabilities
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Setup go
+        uses: actions/setup-go@v6
+        with:
+          go-version: "1.26"
+      - name: Install capslock
+        run: go install github.com/google/capslock/cmd/capslock@latest
+      - name: Check for new capabilities
+        run: ./caps.sh check

AGENTS.md

@@ -53,6 +53,14 @@ go-toml is a TOML library for Go. The goal is to provide an easy-to-use and effi
 - Commit messages must explain **why** the change is needed
 - Keep messages clear and informative even if details are in the PR description
 
+### Capabilities
+
+go-toml tracks system-level capabilities using [capslock](https://github.com/google/capslock). The baseline is in `capability_baseline.txt` and CI enforces that it does not grow.
+
+- **Do not introduce new capabilities.** PRs that increase the capability set (e.g., adding network access, subprocess execution, syscalls) are unlikely to be accepted.
+- If a change causes the capabilities check to fail, do not update the baseline to make it pass. Instead, rethink the approach to avoid requiring new capabilities.
+- To check locally: `./caps.sh check` (requires `capslock` installed via `go install github.com/google/capslock/cmd/capslock@latest`)
+
 ## Pull Request Checklist
 
 Before submitting:
@@ -61,4 +69,5 @@ Before submitting:
 2. No backward-incompatible changes (unless discussed)
 3. Relevant documentation added/updated
 4. No performance regression (verify with benchmarks)
-5. Title is clear and understandable for changelog
+5. Capabilities are not increasing (`./caps.sh check`)
+6. Title is clear and understandable for changelog

CONTRIBUTING.md

@@ -180,6 +180,25 @@ description. Pull requests that lower performance will receive more scrutiny.
 
 [benchstat]: https://pkg.go.dev/golang.org/x/perf/cmd/benchstat
 
+### Capabilities
+
+We use [capslock](https://github.com/google/capslock) to track what
+system-level capabilities (file access, network, syscalls, etc.) each package
+requires. The current baseline is in `capability_baseline.txt`. CI will fail if
+a change introduces a new capability.
+
+**Pull requests that increase the set of capabilities are unlikely to be
+accepted.** go-toml is a parsing library and should not need network access,
+subprocess execution, or other capabilities beyond what it already uses.
+
+If you believe a new capability is genuinely needed, discuss it in an issue
+first. To update the baseline after approval:
+
+```bash
+go install github.com/google/capslock/cmd/capslock@latest
+./caps.sh generate
+```
+
 ### Style
 
 Try to look around and follow the same format and structure as the rest of the

capability_baseline.txt

@@ -0,0 +1 @@
+github.com/pelletier/go-toml/v2: CAPABILITY_REFLECT, CAPABILITY_UNANALYZED, CAPABILITY_UNSAFE_POINTER

caps.sh

@@ -0,0 +1,101 @@
+#!/usr/bin/env bash
+#
+# Generates or checks the capability baseline for go-toml.
+#
+# Usage:
+#   ./caps.sh generate   # regenerate capability_baseline.txt
+#   ./caps.sh check      # check that capabilities haven't grown
+#
+# Requires: go, capslock (go install github.com/google/capslock/cmd/capslock@latest)
+
+set -euo pipefail
+
+BASELINE="capability_baseline.txt"
+CAPSLOCK="${CAPSLOCK:-capslock}"
+
+# Capabilities that must never appear in any package.
+FORBIDDEN_CAPS=(
+    CAPABILITY_NETWORK
+    CAPABILITY_CGO
+    CAPABILITY_EXEC
+)
+
+capslock_to_baseline() {
+    "$CAPSLOCK" -packages=. -output=package -granularity=package \
+        | jq -r 'to_entries | sort_by(.key) | .[] | .key + ": " + (.value | sort | join(", "))'
+}
+
+generate() {
+    capslock_to_baseline > "$BASELINE"
+    echo "Wrote $BASELINE"
+}
+
+check() {
+    if [ ! -f "$BASELINE" ]; then
+        echo "ERROR: $BASELINE not found. Run '$0 generate' first."
+        exit 1
+    fi
+
+    current=$(mktemp)
+    trap 'rm -f "$current"' EXIT
+
+    capslock_to_baseline > "$current"
+
+    failed=0
+
+    # Check for forbidden capabilities in current output.
+    for cap in "${FORBIDDEN_CAPS[@]}"; do
+        if grep -q "$cap" "$current"; then
+            echo "FORBIDDEN capability found: $cap"
+            grep "$cap" "$current"
+            failed=1
+        fi
+    done
+
+    # Extract all unique capability names from baseline and current.
+    baseline_caps=$(grep -oE 'CAPABILITY_[A-Z_]+' "$BASELINE" | sort -u)
+    current_caps=$(grep -oE 'CAPABILITY_[A-Z_]+' "$current" | sort -u)
+
+    # Check for new capability names not in the baseline.
+    new_caps=$(comm -13 <(echo "$baseline_caps") <(echo "$current_caps"))
+    if [ -n "$new_caps" ]; then
+        echo "NEW capabilities detected (not in baseline):"
+        echo "$new_caps"
+        failed=1
+    fi
+
+    # Check for new per-package capabilities (a package gained a capability it didn't have before).
+    while IFS=': ' read -r pkg caps; do
+        baseline_pkg_caps=$(grep "^${pkg}:" "$BASELINE" 2>/dev/null | sed 's/^[^:]*: //' || true)
+        if [ -z "$baseline_pkg_caps" ]; then
+            echo "NEW package with capabilities: $pkg: $caps"
+            failed=1
+            continue
+        fi
+        # Check each capability in current for this package
+        for cap in $(echo "$caps" | tr ', ' '\n' | grep -v '^$'); do
+            if ! echo "$baseline_pkg_caps" | grep -q "$cap"; then
+                echo "NEW capability for $pkg: $cap"
+                failed=1
+            fi
+        done
+    done < "$current"
+
+    if [ "$failed" -eq 1 ]; then
+        echo ""
+        echo "FAILED: capabilities have grown."
+        echo "If this is intentional, run '$0 generate' and commit the updated $BASELINE."
+        exit 1
+    fi
+
+    echo "OK: no new capabilities detected."
+}
+
+case "${1:-}" in
+    generate) generate ;;
+    check)    check ;;
+    *)
+        echo "Usage: $0 {generate|check}"
+        exit 1
+        ;;
+esac