[docs] Add model fallback feature documentation

[github-actions]

Documentation Sync - Model Fallback Feature

This PR synchronizes documentation with the model fallback feature added in commit 1d234dd.

Changes Made

• docs/awf-config-spec.md: Added comprehensive section (§12) documenting model fallback including:

  • Configuration reference for apiProxy.modelFallback with enabled and strategy fields
  • Detailed explanation of the middle-power strategy with capability tier mapping
  • Activation conditions and interaction with model aliases
  • Extended alias syntax supporting per-alias fallback control
  • Introspection via /health endpoint
  • Added apiProxy.modelFallback to CLI mapping section (§5)

• docs/api-proxy-sidecar.md: Added model fallback section covering:

  • Configuration examples (config file and CLI)
  • How middle-power selection works with examples
  • Extended alias syntax with per-alias fallback control
  • How to disable fallback globally or per-alias
  • Updated health check example to include new model_fallback field

Code Changes Referenced

• Commit 1d234dd: feat(api-proxy): add middle-power model fallback with stale-cache recovery (feat(api-proxy): add middle-power model fallback with stale-cache recovery #3607)
  • Added getModelCapabilityTier() and getTierSortedModels() for tier-based model ranking
  • Added selectMiddlePowerFallback() for median model selection
  • Extended model alias syntax to support { patterns: string[], fallback?: boolean }
  • Updated health endpoint to include model_fallback configuration
  • Added comprehensive test coverage for fallback scenarios

Verification

• ✅ Code examples match implementation in containers/api-proxy/model-discovery.js and model-resolver.js
• ✅ Configuration fields documented match schema in src/awf-config-schema.json
• ✅ Capability tiers align with getModelCapabilityTier() function logic
• ✅ Extended alias syntax matches parseModelAliases() and resolveAliasDefinition() implementations
• ✅ Health endpoint response matches management.js output
• ✅ Documentation follows existing style and structure

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🤖 Generated with [Claude Code]((claude.com/redacted)

Generated by Documentation Maintainer · ● 88.7K · ◷

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Documentation Preview

Documentation build failed for this PR. View logs.

Built from commit 185633d

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Smoke Test PASS ✅

• ✅ GitHub MCP: PR [Test Coverage] Add comprehensive test coverage for github-env and copilot-api-resolver #3620 "[Test Coverage] Add comprehensive test coverage for github-env and copilot-api-resolver"
• ✅ GitHub.com connectivity
• ✅ File I/O: /tmp/gh-aw/agent/smoke-test-copilot-byok-26325050446.txt
• ✅ BYOK inference: Running in offline mode (COPILOT_OFFLINE=true) via api-proxy → api.githubcopilot.com

Status: All tests passed
PR: #3617 by @github-actions[bot]

🔑 BYOK report filed by Smoke Copilot BYOK

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Smoke Test Results ✅

• ✅ GitHub API: 2 recent PRs verified
• ✅ GitHub check: playwright_check passed
• ✅ File verify: Smoke test artifact exists

Status: PASS

💥 [THE END] — Illustrated by Smoke Claude

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Smoke Test Results

✅ GitHub MCP: Retrieved PR #3607 - feat(api-proxy): add middle-power model fallback
❓ GitHub.com: HTTP status not available (template variable)
❌ File Test: /tmp/smoke-test-file.txt not found

Status: PARTIAL (MCP working, file test failed)

cc @github-actions[bot]

📰 BREAKING: Report filed by Smoke Copilot

[github-actions]

Smoke Test Codex: FAIL
PRs: feat(api-proxy): add middle-power model fallback with stale-cache recovery; api-proxy: fallback unavailable gpt-5.x requests to highest available family model
✅ GitHub PR review
❌ safeinputs-gh query
✅ Playwright title
❌ Tavily search
✅ File write/read
✅ Discussion comment
✅ npm ci && npm run build
Overall status: FAIL

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• registry.npmjs.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "registry.npmjs.org"

See Network Configuration for more information.

🔮 The oracle has spoken through Smoke Codex

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Service Connectivity Test Results

❌ Redis: TIMEOUT/ERROR
❌ PostgreSQL pg_isready: no response
❌ PostgreSQL SELECT 1: not tested (pg_isready failed)

Result: FAIL — No services reachable via host.docker.internal

🔌 Service connectivity validated by Smoke Services

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🏗️ Build Test Suite Results

Ecosystem	Project	Build/Install	Tests	Status
Bun	elysia	✅	1/1 passed	✅ PASS
Bun	hono	✅	1/1 passed	✅ PASS
C++	fmt	✅	N/A	✅ PASS
C++	json	✅	N/A	✅ PASS
Deno	oak	N/A	1/1 passed	✅ PASS
Deno	std	N/A	1/1 passed	✅ PASS
.NET	hello-world	✅	N/A	✅ PASS
.NET	json-parse	✅	N/A	✅ PASS
Go	color	✅	1/1 passed	✅ PASS
Go	env	✅	1/1 passed	✅ PASS
Go	uuid	✅	1/1 passed	✅ PASS
Java	gson	✅	1/1 passed	✅ PASS
Java	caffeine	✅	1/1 passed	✅ PASS
Node.js	clsx	✅	1/1 passed	✅ PASS
Node.js	execa	✅	1/1 passed	✅ PASS
Node.js	p-limit	✅	1/1 passed	✅ PASS
Rust	fd	✅	1/1 passed	✅ PASS
Rust	zoxide	✅	1/1 passed	✅ PASS

Overall: 8/8 ecosystems passed — ✅ PASS

All build and test operations completed successfully across all ecosystems.

Generated by Build Test Suite for issue #3617 · ● 11.1M · ◷

[github-actions]

Smoke test results: FAIL (Gemini)

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• localhost

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "localhost"

See Network Configuration for more information.

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