Diagram generation: ref-arch-driven procedure + spec validator + KB enrichment

The diagram path now follows a documented standard procedure (lookup
the closest Oracle Architecture Center reference → confirm components
→ author absolute_layout → spec validator → render → visually verify)
and ships persistent guardrails so layout regressions can't recur.

Persistent procedure changes (apply to all users, all sessions):
- tools/diagram_spec_validator.py — geometry checks (CONTAINER_TOO_THIN,
  CONTAINER_PADDING_VIOLATION, LABEL_OVERFLOW_PARENT) run BEFORE either
  renderer (drawio + PPTX). Catches the subnet-collapse / label-overflow
  bugs that the post-render drawio validator missed.
- tools/oci_diagram_gen.py + tools/oci_pptx_diagram_gen.py — call the
  spec validator before emitting any output. Adds mysql / mysql_heatwave
  type aliases.
- tools/archcenter_pattern_lookup.py — scores against cached page
  descriptions (not just the 1-line summary), supports --queries for
  multi-fragment composition, and applies synonym expansion via
  kb/architecture-center/synonyms.yaml so "LB HA cross AD" matches
  "load balancer high availability availability domain".
- kb/architecture-center/synonyms.yaml — canonical synonym table
  (load balancer, autonomous database, data guard, …) used by the
  lookup scorer.

KB enrichment:
- tools/archcenter_description_fetcher.py + 121 cached _description.md
  under kb/diagram/assets/archcenter-refs/<slug>/. Removes the runtime
  dependency on docs.oracle.com when authoring specs and feeds the
  pattern-lookup scorer.
- 110+ cached .drawio / .svg / .png references for offline reuse,
  plus the OCI Toolkit v24.2 import (kb/diagram/assets/oci-toolkit-drawio).

Documentation:
- docs/skill/output-formats.md — new "Standard diagram-generation
  procedure (MANDATORY)" + geometry rules + the new validator entry.
- SKILL.md option 2 — references the mandatory procedure.
- README.md — describes the spec validator, archcenter_pattern_lookup
  and description fetcher, and updates the KB-health table.

Tooling that backs the procedure (cumulative across recent sessions):
tools/archcenter_case_runner.py, archcenter_batch_driver.py,
archcenter_zip_downloader.py, drawio_visual_validator.py,
drawio_fidelity_eval.py, harvest_drawio_icon.py, import_oci_library.py,
oci_pptx_diagram_gen.py, oci_pptx_render.py, refresh_pptx_icon_index.py.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

kb/diagram/assets/archcenter-refs/deploy-adb-db-at-google-cloud/_description.md

@@ -0,0 +1,237 @@
+# Deploy Oracle Autonomous Database on Oracle Database@Google Cloud
+
+- Source: https://docs.oracle.com/en/solutions/deploy-adb-db-at-google-cloud/index.html
+- Date: 2025-03
+- Type: reference-architecture
+- Services: adb-s, adg, google-cloud
+- Tags: database, multicloud, ha-dr, autonomous
+
+## Summary (catalog)
+
+ADB-S on Database@Google Cloud with cross-region ADG. Non-overlapping CIDR between VPC and VCN required. App tier should span 2+ AZs with Google Global Load Balancer for failover.
+
+## Architecture (fetched from source)
+
+Architecture
+
+ 
+
+ 
+This architecture describes some best practices for deploying an Oracle Autonomous Database in Oracle Database@Google Cloud in multiple regions using Oracle Autonomous Data Guard . 
+ 
+
+ 
+Business continuity practices and high-availability topologies should always be considered when designing mission-critical database applications. The architecture diagram shows an application running in two Google Cloud Regions. Users access the application externally through a Google Cloud Load Balancer. Optionally, the Autonomous Database can be configured to have a primary database running in the primary region and a standby database running in the secondary region. In the unlikely event of a Google Cloud Region failure, the standby database in the secondary region can be activated and can become the primary database to serve the application. 
+ 
+
+ 
+The application accesses the database through a private connection to the Oracle Database@Google Cloud subnet. If cross-region business continuity is required, Oracle Autonomous Data Guard can optionally be enabled. If Oracle Autonomous Data Guard is enabled, then Oracle will automatically create a standby database in another
+ Google Cloud Region. Oracle Autonomous Data Guard keeps the primary database and cross-region standby in sync so that the standby
+ database can be activated with minimal data loss in the case of a primary region
+ outage.  Oracle-managed automatic backups are always enabled by default.
+ 
+
+ 
+The following diagram illustrates this reference architecture.
+ 
+ Description of the illustration adb-oracle-db-google-cloud-region.png 
+ adb-oracle-db-google-cloud-region-oracle.zip 
+
+ 
+The architecture has the following components:
+
+ 
+ 
+- Region 
+An Oracle Cloud
+ Infrastructure (OCI) or Google Cloud Region is a localized geographic area that contains one
+ or more data centers. Regions are independent of one another and are in many
+ countries across multiple continents. 
+ 
+In regions where the Oracle Database@Google Cloud services are available, a Google Cloud Region is connected to an OCI Region, with
+ Google Cloud availability zones (AZs) inter-connected to corresponding OCI
+ availability domains (ADs). 
+ 
+ 
+- Google Availability Zone 
+An availability zone is a
+ physically separate data center within a region designed to be available and
+ fault-tolerant. It is close enough to have low-latency connections to other
+ availability zones. 
+
+ 
+ 
+- Google Cloud Project 
+A Google Cloud Project is required to use Google Workspace APIs and build Google Workspace add-ons or apps. A Cloud project forms the basis for creating, enabling, and using all Google Cloud services, including managing APIs, enabling billing, adding and removing collaborators, and managing permissions.
+
+ 
+ 
+- Google Virtual Private Cloud 
+Google Cloud Virtual Private Cloud (VPC) provides networking functionality to Compute Engine virtual machine (VM) instances, Google Kubernetes Engine (GKE) containers, database services, and serverless workloads. VPC provides global, scalable, and flexible networking for your cloud-based service.
+
+ 
+ 
+- Google Subnets 
+Each VPC network consists of one
+ or more IP address ranges called subnets. Subnets are regional resources that
+ have IP address ranges associated with them. 
+
+ 
+ 
+- Google Load Balancer 
+ 
+ 
+Google Load Balancer provides automated traffic distribution from a
+ single entry point to multiple servers in the back end. 
+
+ 
+ 
+- Autonomous Data Guard 
+ Oracle Autonomous Data Guard enables a standby (peer) database to provide data protection and disaster recovery for your Autonomous Database instance. It provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to remain available without interruption. Oracle Data Guard maintains these standby databases as copies of the production database. Then, if the production database becomes unavailable because of a planned or an unplanned outage, you can switch any standby database to the production role, minimizing the downtime associated with the outage.
+ 
+
+ 
+ 
+- Object storage 
+
+ OCI Object Storage provides access to large amounts of structured
+ and unstructured data of any content type,
+ including database backups, analytic data, and
+ rich content such as images and videos. You can
+ safely and securely store data directly from the
+ internet or from within the cloud platform. You
+ can scale storage without experiencing any
+ degradation in performance or service reliability.
+ 
+ 
+
+ 
+Use standard storage for
+ "hot" storage that you need to access quickly,
+ immediately, and frequently. Use archive storage
+ for "cold" storage that you retain for long
+ periods of time and seldom or rarely
+ access.
+
+ 
+ 
+- Oracle Cloud Infrastructure Vault 
+ Oracle Cloud Infrastructure Vault enables you to create and centrally manage the encryption keys that protect your data and the secret credentials that you use to secure access to your resources in the cloud. The default key management is Oracle-managed keys. You can also use customer-managed keys which use OCI Vault . OCI Vault offers a rich set of REST APIs to manage vaults and keys.
+ 
+
+ 
+ 
+ 
+
+ 
+
+ 
+ 
+Considerations
+
+ 
+
+ 
+When implementing this architecture, consider the following:
+
+ 
+ 
+- Network Connectivity 
+When using private
+ connectivity, plan your network connectivity in advance to
+ define your network address space (CIDR) and topologies. You
+ need at least one VPC that you can pair with a corresponding
+ OCI Virtual Cloud Network (VCN). The CIDR blocks for any
+ Google Cloud VPCs and OCI VCNs must not overlap. 
+
+ 
+ 
+- Application Resiliency 
+If using a cross-region
+ standby, then the application tier should also have
+ cross-region redundancy with Google Cloud Global Load
+ Balancer for quick failover.
+
+ 
+ 
+- Disaster Recovery Testing 
+Test your disaster
+ recovery setup by performing a switchover to the standby
+ database on a regular cadence to ensure operational
+ excellence.
+
+ 
+ 
+ 
+
+ 
+
+ 
+ 
+Explore More
+
+ 
+
+ 
+Learn more about Oracle Database@Google Cloud :
+ 
+
+ 
+ 
+- Learn more about Oracle Database@Google Cloud 
+ 
+- Learn about Autonomous Database on Oracle
+ Database@Google Cloud 
+ 
+- Getting started with Autonomous
+ Database on Oracle Database@Google Cloud 
+ (blog)
+ 
+ 
+- Oracle Database@Google Cloud (video)
+ 
+ 
+ 
+ 
+
+ 
+
+ 
+ 
+Acknowledgments
+
+ 
+
+ 
+ 
+- Authors : Tony Politano, Yasin Baskan, Tammy Bednar,
+ Domenick Ficarella, Can Tuzla 
+ 
+ 
+
+ 
+
+ 
+
+ 
+
+ 
+
+ 
+ Title and Copyright Information 
+
+ 
+
+ 
+Deploy an Oracle Autonomous Database in Oracle Database@Google Cloud
+
+ 
+G26642-01
+
+ 
+March 2025
+
+ 
+ Copyright © 2025, 
+
+Oracle and/or its affiliates.

kb/diagram/assets/archcenter-refs/deploy-adb-db-at-google-cloud/readme.txt

@@ -0,0 +1,9 @@
+The diagram you downloaded is available in these formats:
+- DRAWIO
+- SVG
+
+You can customize them for your organization using the associated tools:
+- For DRAWIO format, use draw.io for Confluence, online at diagrams.net, or the desktop app. Go to diagrams.net for more information.
+- For SVG format, use an SVG editor such as Inkscape or Sketsa SVG Editor, which are free and available for Windows, macOS, Linux.
+
+Note that all diagram components are ungrouped and in a single layer.