bug(policy): add policy --target generates an undeployable Cedar statement (wrong action id suffix, resource scope not narrowed)

The issue is in the synthesizeCedar function, likely in dist/cdk/.../synthesizeCedar. Look for where the action ID suffix ___POST:/invocations is hardcoded and where the gatewayArn option is not being passed. The fix involves updating the action suffix to use the tool name and passing the gateway ARN to generate the correct resource constraint. Test by running the reproduction steps and verifying the generated Cedar statement in agentcore.json matches the expected format.

Description

agentcore add policy --target <target-name> generates a Cedar statement that the AgentCore Control API always rejects, so a tool-scoped policy can never be deployed. Two independent defects in the same generated statement:

1. Wrong action id suffix. The CLI emits AgentCore::Action::"<target>___POST:/invocations". The service expects AgentCore::Action::"<target>___<toolName>" and even suggests the correct value in its error.
2. Resource scope not narrowed. The CLI emits resource is AgentCore::Gateway. For a tool-scoped policy the service requires a concrete gateway ARN (resource == AgentCore::Gateway::"<arn>").

synthesizeCedar already accepts a gatewayArn option and produces the ARN-scoped form when it is supplied, but add policy never passes it.

Both defects must be fixed by hand in agentcore.json before agentcore deploy succeeds, which makes add policy --target unusable as shipped.

Steps to Reproduce

agentcore create --name gwprobe2 --no-agent
cd gwprobe2
agentcore add gateway --name toolgw --protocol-type MCP --authorizer-type AWS_IAM
agentcore add gateway-target --type connector --connector web-search \
  --gateway toolgw --name websearch
agentcore add policy-engine --name toolpe --attach-to-gateways toolgw --attach-mode ENFORCE
agentcore add policy --name blockViolence --engine toolpe \
  --form-category contentFilter --form-filters VIOLENCE --form-effect forbid \
  --target websearch
agentcore deploy -y

Generated statement in agentcore.json:

forbid (principal, action == AgentCore::Action::"websearch___POST:/invocations",
        resource is AgentCore::Gateway)
when guardrails { BedrockGuardrails::ContentFilter(["VIOLENCE"], [context.input.prompt])["VIOLENCE"].confidenceScore.greaterThan(decimal("0.2")) };

Expected Behavior

agentcore deploy creates the AWS::BedrockAgentCore::Policy resource.

Actual Behavior

Deploy fails at CreatePolicy. Defect 1 surfaces first:

Resource handler returned message: "Multiple errors occurred during policy parsing/validation:
* for policy `blockViolence_..._0`, unrecognized action
  `AgentCore::Action::"websearch___POST:/invocations"` at line 1, column 30
did you mean `AgentCore::Action::"websearch___WebSearch"`?
* for policy `blockViolence_..._0`, unable to find an applicable action given the
  policy scope constraints
(Service: Bedrock AgentCore Control; Operation: CreatePolicy; Status Code: 400;
 Error Code: ValidationException)"

After correcting the action id by hand, defect 2 surfaces:

Resource handler returned message: "When parsing the policy statement, a constrained
action scope was encountered, please constrain the resource to a specific
AgentCore::Gateway resource when creating tool-specific policies.
(Service: Bedrock AgentCore Control; Operation: CreatePolicy; Status Code: 400;
 Error Code: ValidationException)"

Both corrections applied by hand, the policy deploys and enforces correctly — confirming the statement is the only problem:

forbid (principal, action == AgentCore::Action::"websearch___WebSearch",
        resource == AgentCore::Gateway::"arn:aws:bedrock-agentcore:ap-northeast-1:<account>:gateway/gwprobe2-toolgw-<id>")
when { context.input.query like "*forbidden*" };

Verified end to end over the gateway's MCP endpoint (SigV4):

• query = "washing machine error code" → isError: false, results returned
• query = "this is forbidden content" → Tool Execution Denied: Tool call not allowed due to policy enforcement [Policy evaluation denied due to <policy-id>]

CLI Version

0.30.0

Operating System

macOS

Additional Context

• Region: ap-northeast-1. Gateway authorizerType: AWS_IAM, target type connector / web-search.
• @aws/agentcore-cdk 0.1.0-alpha.53. In dist/cdk/.../synthesizeCedar, the gatewayArn option already selects resource == AgentCore::Gateway::"${arn}" over resource is AgentCore::Gateway, so defect 2 looks like a missing call-site argument rather than a missing feature.
• The action id suffix appears as a literal ___POST:/invocations template in the same function.
• Related but distinct: #1571 (same shape — accepted locally, rejected by CFN — but about a contentFilter enum value), #1910 (EnforcementMode not emitted by the CDK package), #1658 (--generate gateway lookup, closed).
• Docs for this area are still open as #1581, which is why the correct action-id and resource-scope forms are not discoverable today.