AI. Add read_gerrit_cl skill.

Change-Id: I70da1371c01d442511e32f8d35e6106cf4db2af7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/481320
Reviewed-by: Kevin Moore <kevmoo@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

.agents/skills/read_gerrit_cl/SKILL.md

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+---
+name: read_gerrit_cl
+description: Fetch and display the full patch/diff or comments for a Gerrit CL.
+---
+
+# Instructions
+
+Use this skill to inspect a Gerrit Change List (CL).
+This is useful for reviewing code changes, understanding the scope of a modification, checking comments.
+
+## Requirements
+
+The following command-line tools are required:
+
+- `curl`: For making HTTP requests.
+- `jq`: For parsing JSON (needed for comments).
+- `base64`: For decoding patch content (needed for patches).
+
+## Scripts
+
+### 1. Read Patch
+
+Run the `read_patch.sh` script to fetch the unified diff of a CL.
+
+#### Usage
+
+```bash
+./scripts/read_patch.sh <change_number> [patchset]
+```
+
+#### Arguments
+
+1.  `change_number`: The numeric ID of the Gerrit change (e.g., `12345`).
+2.  `patchset` (optional): The patchset number or `current` (default).
+
+#### Example
+
+To fetch the patch for CL 12345 (latest revision):
+
+```bash
+./scripts/read_patch.sh 12345
+```
+
+To fetch a specific revision (e.g. patchset 2):
+
+```bash
+./scripts/read_patch.sh 12345 2
+```
+
+The output will be the unified diff format of the patch.
+
+### 2. Read Comments
+
+Run the `read_comments.sh` script to fetch the comments on a CL.
+
+#### Usage
+
+```bash
+./scripts/read_comments.sh <change_number>
+```
+
+#### Arguments
+
+1.  `change_number`: The numeric ID of the Gerrit change (e.g., `12345`).
+
+#### Example
+
+To fetch comments for CL 12345:
+
+```bash
+./scripts/read_comments.sh 12345
+```
+
+The output will be a JSON object containing the comments.

.agents/skills/read_gerrit_cl/scripts/read_comments.sh

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+#!/bin/bash
+# Copyright (c) 2026, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+set -euo pipefail
+
+# Usage: ./read_comments.sh <change_number>
+# Example: ./read_comments.sh 475600
+
+CHANGE=${1:-}
+if [ -z "$CHANGE" ]; then
+  echo "Usage: $0 <change_number>"
+  exit 1
+fi
+
+if [[ ! "$CHANGE" =~ ^[0-9]+$ ]]; then
+  echo "Error: change_number must be numeric" >&2
+  exit 1
+fi
+
+command -v curl >/dev/null || { echo "Error: curl is required" >&2; exit 127; }
+command -v jq   >/dev/null || { echo "Error: jq is required"   >&2; exit 127; }
+
+GERRIT='https://dart-review.googlesource.com'
+URL="$GERRIT/changes/$CHANGE/comments"
+
+# 1. 'curl -fSsL' fetches data, follows redirects, and fails on server errors.
+# 2. 'sed 1d' strips Gerrit's XSSI prefix (the magic ')]}' string) to make it valid JSON.
+# 3. 'jq' parses the cleaned string, validates it, and pretty-prints it for readability.
+curl -fSsL "$URL" | sed '1d' | jq '.'

.agents/skills/read_gerrit_cl/scripts/read_patch.sh

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+#!/bin/bash
+# Copyright (c) 2026, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+set -euo pipefail
+
+# Usage: ./read_patch.sh <change_number> [patchset]
+# Example: ./read_patch.sh 459740
+# Example: ./read_patch.sh 459740 2
+
+CHANGE=${1:-}
+if [ -z "$CHANGE" ]; then
+  echo "Usage: $0 <change_number> [patchset]"
+  exit 1
+fi
+
+if [[ ! "$CHANGE" =~ ^[0-9]+$ ]]; then
+  echo "Error: change_number must be numeric" >&2
+  exit 1
+fi
+
+PATCHSET=${2:-current}
+
+if [[ "$PATCHSET" != "current" && ! "$PATCHSET" =~ ^[0-9]+$ ]]; then
+  echo "Error: patchset must be 'current' or numeric" >&2
+  exit 1
+fi
+
+command -v curl >/dev/null || { echo "Error: curl is required" >&2; exit 127; }
+command -v base64 >/dev/null || { echo "Error: base64 is required" >&2; exit 127; }
+
+GERRIT='https://dart-review.googlesource.com'
+URL="$GERRIT/changes/$CHANGE/revisions/$PATCHSET/patch"
+
+# 1. 'curl -fSsL' fetches data, follows redirects, and fails on server errors.
+# 2. Gerrit API /patch endpoint returns base64 encoded content.
+# 3. 'base64 --decode' decodes it back to the original unified diff text.
+curl -fSsL "$URL" | base64 --decode