ci: add static check for agent policy coverage

Add ci/check_agent_policy_coverage.sh, a static check that asserts
every RPC method declared in the AgentService block of agent.proto has:

1. A policy gate (is_allowed or do_set_policy call) in the corresponding
   handler in src/agent/src/rpc.rs.
2. A default rule entry in src/tools/genpolicy/rules.rego.

This prevents future handlers from silently bypassing the policy
boundary — the gap that prompted this work was MemAgentMemcgSet and
MemAgentCompactSet, which previously had no is_allowed call and no
rules.rego entry.

The script is self-contained and can be run standalone from any
directory in the repository tree.

Generated-By: IBM Bob
Assisted-by: Google AI Mode
Signed-off-by: stevenhorsman <steven@uk.ibm.com>

ci/check_agent_policy_coverage.sh

@@ -0,0 +1,123 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2026 IBM Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# check_agent_policy_coverage.sh - Static check that every RPC method in
+# AgentService has a policy gate in rpc.rs and a default rule in rules.rego.
+#
+# Usage: ./ci/check_agent_policy_coverage.sh
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+[[ -n "${DEBUG:-}" ]] && set -o xtrace
+
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+repo_root="$(cd "${script_dir}/.." && pwd)"
+
+PROTO="${repo_root}/src/libs/protocols/protos/agent.proto"
+RPC_RS="${repo_root}/src/agent/src/rpc.rs"
+RULES_REGO="${repo_root}/src/tools/genpolicy/rules.rego"
+
+# ---------------------------------------------------------------------------
+# 1. Extract unique request types from AgentService in the proto file
+# ---------------------------------------------------------------------------
+request_types=()
+
+while IFS= read -r req_type; do
+    [[ -n "${req_type}" ]] && request_types+=("${req_type}")
+done < <(
+    awk '
+    /^service AgentService/,/^}/ {
+        if ($0 ~ /^[[:space:]]*rpc[[:space:]]+/) {
+            match($0, /\([A-Za-z0-9_]+\)/)
+            if (RSTART > 0) {
+                print substr($0, RSTART + 1, RLENGTH - 2)
+            }
+        }
+    }
+    ' "${PROTO}" | sort -u
+)
+
+if [[ ${#request_types[@]} -eq 0 ]]; then
+    echo "ERROR: failed to extract any request types from ${PROTO}" >&2
+    exit 1
+fi
+
+echo "Checking ${#request_types[@]} unique request types from AgentService..."
+
+# ---------------------------------------------------------------------------
+# 2. Pre-process rpc.rs into an in-memory string cache
+#    This isolates the impl block and flattens newlines so multi-line
+#    method headers match perfectly on both Mac and Linux.
+# ---------------------------------------------------------------------------
+impl_start=$(grep -m 1 -n 'impl agent_ttrpc::AgentService for AgentService' "${RPC_RS}" | cut -d: -f1 || true)
+if [[ -z "${impl_start}" ]]; then
+    echo "ERROR: could not find impl block in ${RPC_RS}" >&2
+    exit 1
+fi
+
+# Read from impl_start onwards, flatten all whitespace into spaces for easy matching
+rpc_cache=$(tail -n +"${impl_start}" "${RPC_RS}" | tr '\n' ' ' | tr -s ' ')
+
+# ---------------------------------------------------------------------------
+# 3. Check each request type for policy gates and rules
+# ---------------------------------------------------------------------------
+missing_rpc=()
+missing_rego=()
+
+for req_type in "${request_types[@]}"; do
+    # --- Check rpc.rs ---
+    # Match the handler function that takes this request type as its parameter,
+    # extracting from "async fn" up to the closing "}" of that method body.
+    method_block=$(grep -oE "async fn [A-Za-z0-9_]+[^}]+(req|config)[[:space:]]*:[[:space:]]*(protocols::agent::)?${req_type}[^}]+}" <<< "${rpc_cache}" | head -1 || true)
+
+    if [[ -z "${method_block}" ]]; then
+        missing_rpc+=("${req_type}  [no handler found in rpc.rs impl block]")
+        continue
+    fi
+
+    # Ensure the method body actually invokes the required security assertions
+    if ! grep -qE 'is_allowed|do_set_policy' <<< "${method_block}"; then
+        missing_rpc+=("${req_type}  [handler found, but has no is_allowed/do_set_policy call]")
+    fi
+
+    # --- Check rules.rego ---
+    if ! grep -q "default ${req_type} " "${RULES_REGO}"; then
+        missing_rego+=("${req_type}")
+    fi
+done
+
+# ---------------------------------------------------------------------------
+# 4. Report results
+# ---------------------------------------------------------------------------
+failed=0
+
+if (( ${#missing_rpc[@]} > 0 )); then
+    echo -e "\nFAIL: The following request types are missing a policy gate in ${RPC_RS}:"
+    for entry in "${missing_rpc[@]}"; do
+        echo "  - ${entry}"
+    done
+    failed=1
+fi
+
+if (( ${#missing_rego[@]} > 0 )); then
+    echo -e "\nFAIL: The following request types are missing a 'default <TypeName>' rule in ${RULES_REGO}:"
+    for entry in "${missing_rego[@]}"; do
+        echo "  - ${entry}"
+    done
+    echo -e "\n  Add entries like:"
+    for entry in "${missing_rego[@]}"; do
+        echo "    default ${entry} := false"
+    done
+    failed=1
+fi
+
+if (( failed == 0 )); then
+    echo "OK: all ${#request_types[@]} AgentService request types have policy gates and rules.rego entries."
+fi
+
+exit "${failed}"