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Seam

Seam is the agent-in-the-middle proxy. It owns HTTP, SSE, WebSocket, and MCP stdio transport handling so it can preserve raw bytes, decode semantic messages, rewrite complete messages, and record schema-valid transcripts.

Current capabilities:

  • Passive tap for HTTP, SSE, WebSocket, and MCP stdio.
  • Active proxy for complete HTTP/SSE/WebSocket/stdio messages.
  • A2A, MCP, and unknown-frame decoding.
  • Hash-chained transcript writer and offline verifier.
  • YAML rewrite rules with exact matches, predicates, and mutations.
  • Injection primitives: set, delete, append, insert, merge, replace, and local payload files.
  • Localhost API with /deliver.
  • Robustness scenario runner.
  • Version/build metadata, release archives, tagged release workflow, and release smoke automation with bundled rules, scenarios, examples, quickstart, and schemas.
  • Capability-preserving hardening defaults: loopback listeners, explicit remote opt-ins, no automatic redirect following, API token support, and optional profile manifests that expand to ordinary flags.
  • Operator completion commands: session status, session tail, rules explain, and transcript redact for live offensive usability and report-safe review copies.

Start with the Operator Handbook, then use the Command Reference, Active Rewrite, Rules, A2A Playbooks, MCP Playbooks, and Offensive Examples for concrete operations. Seam is the field tool: it can observe, rewrite, trace, inspect, and verify without Assay.

Downstream Artifacts

Seam transcripts are consumed by meshmapper ingestion and can be referenced by optional Assay findings. The localhost API is the delivery contract for Assay cases.

Use robustness scenarios to show that a transport and rule path survives repeated runs. Use Assay when the claim depends on whether a side effect actually happened.

Use profiles as visible presets for common operator postures. They are convenience manifests, not a policy engine; explicit flags remain the source of truth.

Use Evidence Handoff when moving from Seam transcripts to meshmapper graphing or optional Assay validation.