Simplify Bicep infrastructure: flat module library replacing framework pattern

[therealjohn]

Problem

The Bicep infra had become a generic framework with business logic — JSON array parameters parsed at deploy-time to dynamically decide which resources to create, filter()/map() operations, deeply nested ternary outputs, dual code
paths for new vs. existing projects, and outputs for resource types the template doesn't use. ~2,877 lines across 14 files for a "basic starter."

Changes

Architecture: framework → flat module library

Replace the core/ directory tree (deeply nested, interdependent modules with a 414-line "God module") with a flat modules/ directory where each module is self-contained: creates its resource + Foundry Project connection + RBAC.

Before	After
infra/core/ai/ai-project.bicep (414 lines, creates everything conditionally)	infra/modules/ai-project.bicep (216 lines, AI Account + Project + monitoring + RBAC)
infra/core/ai/existing-ai-project.bicep (70 lines, duplicate output shape)	Merged into ai-project.bicep — single module handles both paths
infra/core/monitor/applicationinsights-dashboard.bicep (1,236 lines!)	Removed — unused dead code
14 files, ~2,877 lines	8 files, ~819 lines

Modules (pick-and-choose per template):

• ai-project.bicep — AI Account + Project + Capability Host + Log Analytics + App Insights + RBAC + connections
• acr.bicep — Container Registry + connection + role assignments
• connection.bicep — Generic Foundry Project connection creator
• storage.bicep — Storage account + connection + RBAC
• ai-search.bicep — AI Search + knowledge container + connection + RBAC
• bing-grounding.bicep — Bing Search + connection + RBAC

Removed:

• abbreviations.json (137 lines) — used once, inlined
• applicationinsights-dashboard.bicep (1,236 lines) — dead code, never invoked
• existing-ai-project.bicep — merged into ai-project.bicep
• acr-role-assignment.bicep — inlined into acr.bicep
• bing_custom_grounding.bicep — no current samples use it
• dependentResourcesType and JSON array resource discovery pattern
• enableHostedAgents, enableCapabilityHost, enableMonitoring toggle flags
• @allowed location list (25 entries) — handled by azd extension via azure-dev#7930

Output variable renames to match platform-injected environment variables:

• AZURE_AI_PROJECT_ENDPOINT → FOUNDRY_PROJECT_ENDPOINT
• AZURE_AI_PROJECT_ID / AZURE_AI_FOUNDRY_PROJECT_ID → FOUNDRY_PROJECT_ARM_ID
• APPLICATIONINSIGHTS_CONNECTION_STRING — already matches, unchanged

CI: Bicep validation workflow (.github/workflows/bicep-validate.yml)

• Layer 1 — bicep lint + bicep build on all files (no Azure creds needed)
• Layer 2 — az deployment sub validate against 4 scenario parameter files
• Layer 3 — az deployment sub what-if preview for each scenario

Test scenarios:

Scenario	Code paths exercised
new-project	New account + project + ACR (default)
new-project-with-model	Above + model deployment array
existing-project	Existing project + existing ACR connection (skip creation)
existing-project-new-acr	Existing project + new ACR creation

Summary

27 files changed, 949 insertions(+), 2,877 deletions(-)

Metric	Before	After
Files (basic template)	14	5
Lines (basic template)	~2,877	~521
main.parameters.json params	21	15
Ternary outputs in main.bicep	18	2
JSON array parsing for resources	4 vars	0