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Merged
pelikhan merged 6 commits into from
Oct 2, 2026
Merged

Claude: default to strict MCP configuration #64970

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e124037
Initial plan
Copilot Oct 2, 2026
43e8f4e
Enable strict MCP configuration for Claude engine
Copilot Oct 2, 2026
0fa4e37
Apply remaining changes
Copilot Oct 2, 2026
76424a9
Merge branch 'main' into copilot/fix-strict-mcp-config-issue
github-actions[bot] Oct 2, 2026
89202d3
Document strict Claude MCP migration
Copilot Oct 2, 2026
78842e1
Restore generated action pins
Copilot Oct 2, 2026
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11 changes: 11 additions & 0 deletions .changeset/major-strict-claude-mcp-config.md
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2 changes: 1 addition & 1 deletion pkg/workflow/claude_engine.go
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Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,7 @@ func (e *ClaudeEngine) GetExecutionSteps(workflowData *WorkflowData, logFile str
// the --mcp-config argument (kept outside shellJoinArgs for runtime ${RUNNER_TEMP} expansion),
// and the allowed-tools string (reused for the comment annotation).
func (e *ClaudeEngine) buildClaudeCliArgs(workflowData *WorkflowData, toolsWithMountedCLIs map[string]any, logFile string) (claudeArgs []string, mcpConfigArg string, allowedTools string) {
claudeArgs = append(claudeArgs, "--print", "--no-chrome")
claudeArgs = append(claudeArgs, "--print", "--no-chrome", "--strict-mcp-config")

Copilot AI Oct 2, 2026

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Added .changeset/major-strict-claude-mcp-config.md with a major changeset and migration guidance to declare MCP servers through workflow mcp-servers: frontmatter (commit 89202d3).

@github-actions github-actions Bot Oct 2, 2026

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✅ Good addition! The --strict-mcp-config flag ensures Claude ignores ambient .mcp.json files and only uses the explicitly configured MCP servers. This prevents unintended MCP connections and reduces noise in logs. Consider adding a comment explaining why this flag is always included, even for workflows without MCP servers.

Copilot AI Oct 2, 2026

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Added a code comment explaining why ambient MCP config is always disabled; this follow-up is in commit 068d31b, after the PR’s reported merge head.


if workflowData.EngineConfig != nil && workflowData.EngineConfig.MaxTurns != "" {
claudeLog.Printf("Setting max turns: %s", workflowData.EngineConfig.MaxTurns)
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12 changes: 12 additions & 0 deletions pkg/workflow/claude_engine_test.go
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Expand Up @@ -111,6 +111,10 @@ func TestClaudeEngine(t *testing.T) {
t.Errorf("Expected --print flag in step: %s", stepContent)
}

if !strings.Contains(stepContent, "--strict-mcp-config") {

@github-actions github-actions Bot Oct 2, 2026

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👍 The new test assertion for --strict-mcp-config is well-placed. It validates that the flag is present even when no MCP servers are configured, which ensures the behavior is unconditional. Consider also testing that the flag appears before --allowed-tools to verify argument ordering remains stable.

Copilot AI Oct 2, 2026

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Added an assertion that --strict-mcp-config precedes --allowed-tools; this follow-up is in commit 068d31b, after the PR’s reported merge head.

t.Errorf("Expected --strict-mcp-config in CLI args even without MCP servers: %s", stepContent)
}

if !strings.Contains(stepContent, "--permission-mode acceptEdits") {
t.Errorf("Expected --permission-mode acceptEdits in CLI args: %s", stepContent)
}
Expand Down Expand Up @@ -654,6 +658,10 @@ func TestClaudeEngineWithMCPServers(t *testing.T) {
t.Errorf("Expected --mcp-config in CLI args when MCP servers are configured: %s", stepContent)
}

if !strings.Contains(stepContent, "--strict-mcp-config") {
t.Errorf("Expected --strict-mcp-config in CLI args when MCP servers are configured: %s", stepContent)
}

// When MCP servers are configured, GH_AW_MCP_CONFIG SHOULD be present
if !strings.Contains(stepContent, "GH_AW_MCP_CONFIG: ${{ runner.temp }}/gh-aw/mcp-config/mcp-servers.json") {
t.Errorf("Expected GH_AW_MCP_CONFIG environment variable when MCP servers are configured: %s", stepContent)
Expand Down Expand Up @@ -688,6 +696,10 @@ func TestClaudeEngineWithSafeOutputs(t *testing.T) {
t.Errorf("Expected --mcp-config in CLI args when safe-outputs are configured: %s", stepContent)
}

if !strings.Contains(stepContent, "--strict-mcp-config") {
t.Errorf("Expected --strict-mcp-config in CLI args when safe-outputs are configured: %s", stepContent)
}

// When safe-outputs is configured, GH_AW_MCP_CONFIG SHOULD be present
if !strings.Contains(stepContent, "GH_AW_MCP_CONFIG: ${{ runner.temp }}/gh-aw/mcp-config/mcp-servers.json") {
t.Errorf("Expected GH_AW_MCP_CONFIG environment variable when safe-outputs are configured: %s", stepContent)
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2 changes: 1 addition & 1 deletion pkg/workflow/testdata/TestWasmGolden_AllEngines/claude.golden
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Expand Up @@ -635,7 +635,7 @@ jobs:
GH_AW_AWF_ATTEMPT_LOG_NAME=claude \
bash "${RUNNER_TEMP}/gh-aw/actions/run_awf_with_startup_retries.sh" -- \
awf --config "${RUNNER_TEMP}/gh-aw/awf-config.json" --container-workdir "${GITHUB_WORKSPACE}" --mount "${RUNNER_TEMP}/gh-aw:${RUNNER_TEMP}/gh-aw:ro" --mount "${RUNNER_TEMP}/gh-aw:/host${RUNNER_TEMP}/gh-aw:ro" ${GH_AW_TOOL_CACHE_MOUNT:+--mount "$GH_AW_TOOL_CACHE_MOUNT"} ${GH_AW_DOCKER_HOST:+--docker-host "$GH_AW_DOCKER_HOST"} --tty --env-all --exclude-env ACTIONS_ID_TOKEN_REQUEST_TOKEN --exclude-env ACTIONS_ID_TOKEN_REQUEST_URL --exclude-env ANTHROPIC_API_KEY --exclude-env GITHUB_MCP_SERVER_TOKEN --exclude-env MCP_GATEWAY_AGENT_ID --mount /tmp/gh-aw:/tmp/gh-aw:rw --log-level info --skip-pull \
-- /bin/bash -c 'set +o histexpand; : "${RUNNER_TOOL_CACHE:?RUNNER_TOOL_CACHE must be set}"; GH_AW_TOOL_CACHE="$RUNNER_TOOL_CACHE"; GH_AW_TOOL_BINS="$(find "$GH_AW_TOOL_CACHE" -maxdepth 5 -type d -name bin 2>/dev/null | tr '\''\n'\'' '\'':'\'')"; GH_AW_TOOL_BINS="${GH_AW_TOOL_BINS%:}"; export PATH="$PATH${GH_AW_TOOL_BINS:+:}$GH_AW_TOOL_BINS"; [ -n "$GOROOT" ] && export PATH="$GOROOT/bin:$PATH" || true; [ -n "$ERLANG_HOME" ] && export PATH="$ERLANG_HOME/bin:$PATH" || true && GH_AW_NODE_EXEC="${GH_AW_NODE_BIN:-}"; if [ -z "$GH_AW_NODE_EXEC" ] || [ ! -x "$GH_AW_NODE_EXEC" ]; then GH_AW_NODE_EXEC="$(command -v node 2>/dev/null || true)"; fi; if [ -z "$GH_AW_NODE_EXEC" ]; then echo "node runtime missing on this runner — check runtimes.node in workflow YAML" >&2; exit 127; fi; GH_AW_NPM_GLOBAL_ROOT="$(npm root -g 2>/dev/null || true)"; if [ -n "$GH_AW_NPM_GLOBAL_ROOT" ]; then export NODE_PATH="${GH_AW_NPM_GLOBAL_ROOT}${NODE_PATH:+:${NODE_PATH}}"; fi; "$GH_AW_NODE_EXEC" ${RUNNER_TEMP}/gh-aw/actions/claude_harness.cjs claude --print --no-chrome --allowed-tools '\''Bash,BashOutput,Edit,Edit(/tmp/*),ExitPlanMode,Glob,Grep,KillBash,LS,MultiEdit,MultiEdit(/tmp/*),NotebookEdit,NotebookRead,Read,Read(/tmp/*),Skill,Task,TodoWrite,Write,Write(/tmp/*),mcp__github__actions_get,mcp__github__actions_list,mcp__github__get_code_scanning_alert,mcp__github__get_commit,mcp__github__get_dependabot_alert,mcp__github__get_discussion,mcp__github__get_discussion_comments,mcp__github__get_file_contents,mcp__github__get_job_logs,mcp__github__get_label,mcp__github__get_latest_release,mcp__github__get_me,mcp__github__get_notification_details,mcp__github__get_pull_request,mcp__github__get_pull_request_comments,mcp__github__get_pull_request_diff,mcp__github__get_pull_request_files,mcp__github__get_pull_request_review_comments,mcp__github__get_pull_request_reviews,mcp__github__get_pull_request_status,mcp__github__get_release_by_tag,mcp__github__get_secret_scanning_alert,mcp__github__get_tag,mcp__github__issue_read,mcp__github__list_branches,mcp__github__list_code_scanning_alerts,mcp__github__list_commits,mcp__github__list_dependabot_alerts,mcp__github__list_discussion_categories,mcp__github__list_discussions,mcp__github__list_issue_types,mcp__github__list_issues,mcp__github__list_label,mcp__github__list_notifications,mcp__github__list_pull_requests,mcp__github__list_releases,mcp__github__list_secret_scanning_alerts,mcp__github__list_starred_repositories,mcp__github__list_tags,mcp__github__pull_request_read,mcp__github__search_code,mcp__github__search_issues,mcp__github__search_orgs,mcp__github__search_pull_requests,mcp__github__search_repositories,mcp__github__search_users'\'' --debug-file /tmp/gh-aw/claude-debug.log --verbose --permission-mode acceptEdits --output-format stream-json --mcp-config "${RUNNER_TEMP}/gh-aw/mcp-config/mcp-servers.json" --prompt-file /tmp/gh-aw/aw-prompts/prompt.txt${GH_AW_MODEL_DETECTION_CLAUDE:+ --model "$GH_AW_MODEL_DETECTION_CLAUDE"}'
-- /bin/bash -c 'set +o histexpand; : "${RUNNER_TOOL_CACHE:?RUNNER_TOOL_CACHE must be set}"; GH_AW_TOOL_CACHE="$RUNNER_TOOL_CACHE"; GH_AW_TOOL_BINS="$(find "$GH_AW_TOOL_CACHE" -maxdepth 5 -type d -name bin 2>/dev/null | tr '\''\n'\'' '\'':'\'')"; GH_AW_TOOL_BINS="${GH_AW_TOOL_BINS%:}"; export PATH="$PATH${GH_AW_TOOL_BINS:+:}$GH_AW_TOOL_BINS"; [ -n "$GOROOT" ] && export PATH="$GOROOT/bin:$PATH" || true; [ -n "$ERLANG_HOME" ] && export PATH="$ERLANG_HOME/bin:$PATH" || true && GH_AW_NODE_EXEC="${GH_AW_NODE_BIN:-}"; if [ -z "$GH_AW_NODE_EXEC" ] || [ ! -x "$GH_AW_NODE_EXEC" ]; then GH_AW_NODE_EXEC="$(command -v node 2>/dev/null || true)"; fi; if [ -z "$GH_AW_NODE_EXEC" ]; then echo "node runtime missing on this runner — check runtimes.node in workflow YAML" >&2; exit 127; fi; GH_AW_NPM_GLOBAL_ROOT="$(npm root -g 2>/dev/null || true)"; if [ -n "$GH_AW_NPM_GLOBAL_ROOT" ]; then export NODE_PATH="${GH_AW_NPM_GLOBAL_ROOT}${NODE_PATH:+:${NODE_PATH}}"; fi; "$GH_AW_NODE_EXEC" ${RUNNER_TEMP}/gh-aw/actions/claude_harness.cjs claude --print --no-chrome --strict-mcp-config --allowed-tools '\''Bash,BashOutput,Edit,Edit(/tmp/*),ExitPlanMode,Glob,Grep,KillBash,LS,MultiEdit,MultiEdit(/tmp/*),NotebookEdit,NotebookRead,Read,Read(/tmp/*),Skill,Task,TodoWrite,Write,Write(/tmp/*),mcp__github__actions_get,mcp__github__actions_list,mcp__github__get_code_scanning_alert,mcp__github__get_commit,mcp__github__get_dependabot_alert,mcp__github__get_discussion,mcp__github__get_discussion_comments,mcp__github__get_file_contents,mcp__github__get_job_logs,mcp__github__get_label,mcp__github__get_latest_release,mcp__github__get_me,mcp__github__get_notification_details,mcp__github__get_pull_request,mcp__github__get_pull_request_comments,mcp__github__get_pull_request_diff,mcp__github__get_pull_request_files,mcp__github__get_pull_request_review_comments,mcp__github__get_pull_request_reviews,mcp__github__get_pull_request_status,mcp__github__get_release_by_tag,mcp__github__get_secret_scanning_alert,mcp__github__get_tag,mcp__github__issue_read,mcp__github__list_branches,mcp__github__list_code_scanning_alerts,mcp__github__list_commits,mcp__github__list_dependabot_alerts,mcp__github__list_discussion_categories,mcp__github__list_discussions,mcp__github__list_issue_types,mcp__github__list_issues,mcp__github__list_label,mcp__github__list_notifications,mcp__github__list_pull_requests,mcp__github__list_releases,mcp__github__list_secret_scanning_alerts,mcp__github__list_starred_repositories,mcp__github__list_tags,mcp__github__pull_request_read,mcp__github__search_code,mcp__github__search_issues,mcp__github__search_orgs,mcp__github__search_pull_requests,mcp__github__search_repositories,mcp__github__search_users'\'' --debug-file /tmp/gh-aw/claude-debug.log --verbose --permission-mode acceptEdits --output-format stream-json --mcp-config "${RUNNER_TEMP}/gh-aw/mcp-config/mcp-servers.json" --prompt-file /tmp/gh-aw/aw-prompts/prompt.txt${GH_AW_MODEL_DETECTION_CLAUDE:+ --model "$GH_AW_MODEL_DETECTION_CLAUDE"}'
env:
ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
ANTHROPIC_MAX_RETRIES: 0
Expand Down
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