feat(examples): add collaborative agents demo — Internet of Agents with semantic memory

[Subhajitdas99]

Summary

• Problem: No working example in Bindu showing multiple agents communicating with each other over the A2A protocol — making it hard for developers to understand the Internet of Agents vision in practice.
• Why it matters: This is the core of what Bindu is building. Developers need a concrete, runnable example to see agents with DID identities calling each other over A2A, not just a single agent running in isolation.
• What changed: Added examples/collaborative-agents/ — three bindufied agents that communicate over the A2A protocol, with semantic memory and a coordinator pattern. Verified working end-to-end.
• What did NOT change: No core Bindu code touched. Pure example addition.

Change Type

• Feature
• Documentation

Scope

• Documentation

Linked Issue/PR

• Related to NightSky / Internet of Agents vision in README

User-Visible / Behavior Changes

New runnable example at examples/collaborative-agents/.

Agent	Port	Role
research_agent.py	3773	Searches web via DuckDuckGo + LLM
memory_agent.py	3774	Stores/retrieves via semantic similarity
coordinator_agent.py	3775	Orchestrates the other two over A2A

Each agent has its own Bindu DID identity. Coordinator calls research and memory agents over HTTP using A2A message/send + tasks/get — real agent-to-agent communication.

Security Impact

• New permissions/capabilities? No
• Secrets/credentials handling changed? No — API key via .env, excluded via .gitignore
• New/changed network calls? Yes — agents call each other over localhost HTTP
• Database schema/migration changes? No
• Authentication/authorization changes? No

Verification

Steps to Test

1. cd examples/collaborative-agents
2. pip install -r requirements.txt
3. Set OPENROUTER_API_KEY in .env
4. Run python research_agent.py in Terminal 1
5. Run python memory_agent.py in Terminal 2
6. Run python coordinator_agent.py in Terminal 3
7. Send query to coordinator at http://localhost:3775/ — see README for curl commands

Actual Behavior — Verified

• All three agents start with unique DID identities
• First query: cache miss → research agent → web answer → stored in memory
• Second identical query: cache hit → instant answer from memory
• Every response includes did.message.signature (cryptographic DID signing)

Evidence

• Verified working end-to-end locally
• DID signatures present on all responses
• Memory retrieval confirmed on repeat queries

Human Verification

• Verified: First query cache miss → research → store. Second query cache hit → instant memory response.
• Edge cases: API key not set → research fails gracefully. Empty memory → coordinator falls back correctly.
• Not verified: Multi-user concurrent queries (in-memory store is single-process)

Compatibility / Migration

• Backward compatible? Yes — pure addition, nothing modified
• Config/env changes? No
• Database migration needed? No

Failure Recovery

• How to disable: Don't run the example — zero impact on core Bindu
• Known symptoms: If OpenRouter unreachable, research agent fails gracefully

Risks and Mitigations

• Risk: In-memory semantic store lost on process restart
  • Mitigation: Scoped as demo only. Production would use Postgres + pgvector. Documented in README.

Checklist

• Verified working end-to-end locally
• .env excluded via .gitignore
• requirements.txt included
• README with architecture, setup, and curl commands for Linux + Windows
• Zero core Bindu code changed