Feat/rag

[vinodvx]

Description

Adds first-class RAG support to agent-sdk-go via a pluggable interfaces.Retriever API, with agentic, prefetch, and hybrid retrieval modes integrated into the Temporal agent workflow. Also bumps the Go toolchain to 1.26.

What's included

• Retriever modes — agentic (LLM calls retriever as a tool), prefetch (retrieve before each LLM call), and hybrid (both)
• Workflow integration — AgentRetrieverActivity for prefetch/hybrid; retrieved context injected into LLM prompts; retriever exposed as a tool in agentic/hybrid
• Built-in backends — pkg/retriever/weaviate and pkg/retriever/pgvector (cosine search, configurable top-k/min-score)
• Agent config — WithRetrievers, WithRetrieverMode; retriever config included in agent fingerprint for worker alignment
• Examples — examples/agent_with_retriever/ with shared config, sample KB, Docker setup/cleanup scripts (pgvector includes verify.sh)
• Docs — README RAG section, capabilities/TOC updates, env.sample vars
• Go 1.26 — go.mod updated to go 1.26 / toolchain go1.26.0; Makefile and CI/lint tooling adjusted as needed

Test plan

• Run Weaviate example in agentic, prefetch, and hybrid modes
• Run pgvector example in all three modes; confirm verify.sh returns expected scores
• Confirm agent and worker use the same retriever config (no fingerprint mismatch)
• Verify build/test with Go 1.26
• Run make test for retriever and workflow packages

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactor / chore

Related issues

Fixes #16

Checklist

• I have run make lint and make test locally
• I have run make tidy if I added or removed dependencies
• Commit messages follow conventional commits (e.g. feat:, fix:, docs:)
• I have added/updated tests for my changes
• Documentation is updated if needed

[codecov]

Codecov Report

❌ Patch coverage is 88.90815% with 64 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/retriever/pgvector/retriever.go	81.88%	24 Missing and 1 partial ⚠️
pkg/retriever/weaviate/retriever.go	89.93%	13 Missing and 2 partials ⚠️
internal/runtime/temporal/agent_workflow.go	91.48%	5 Missing and 3 partials ⚠️
pkg/agent/mcp.go	60.00%	4 Missing and 2 partials ⚠️
internal/runtime/temporal/config.go	0.00%	3 Missing ⚠️
pkg/agent/config.go	97.18%	1 Missing and 1 partial ⚠️
pkg/agent/retriever.go	97.72%	1 Missing and 1 partial ⚠️
internal/runtime/temporal/runtime.go	0.00%	1 Missing ⚠️
pkg/agent/a2a.go	93.33%	1 Missing ⚠️
pkg/agent/runtime_factory.go	0.00%	1 Missing ⚠️

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