echo6-docs/PHASE6_DECISION.md

Phase 6 Decision Summary

Generated: 2026-04-09

1. Is Hookshot the Right Choice?

NO. Hookshot cannot be used for this use case.

Reason: Hookshot's E2EE implementation is incompatible with MAS (Matrix Authentication Service). Echo6's Synapse uses MAS. All mautrix-signal portal rooms use E2BE encryption. Hookshot cannot establish crypto sessions when MAS is active (GitHub issues #1084, #980 — both OPEN as of March 2026). The webhook payloads would contain useless ciphertext, not plaintext.

This is a hard blocker with no workaround short of disabling MAS (breaks all user auth) or disabling E2BE on the bridge (exposes Signal messages in transit).

2. Recommended Alternative: Synapse Retention + Export Script

Instead of hookshot, a much simpler approach achieves the same goal:

Step 1: Synapse Config (2 lines)

redaction_retention_period: null     # Never censor redacted content
experimental_features:
  msc2815_enabled: true              # Allow moderator access to redacted content

This preserves ALL event content in Synapse's Postgres forever, including redacted messages. MSC2815 provides API access to the original content.

Step 2: Export Script (cron job, no bot)

A Python script that:

• Runs nightly via cron on Contabo
• Queries Synapse admin API for events in bridged rooms
• Writes JSONL + markdown exports to /mnt/library/Archives/Signal/
• No E2EE handling needed — admin API returns server-side decrypted content
• No bot account, no device verification, no crypto key management

Why This Is Better Than Hookshot

Concern	Hookshot	Synapse Retention + Export
E2EE + MAS	BROKEN	Not applicable (admin API)
Per-room config	Manual per room	Automatic (all rooms)
New portal auto-join	Requires automation	Not needed (queries DB)
Backfill historical	No backfill	Full history available
Infrastructure	New container + Redis	2-line config + cron script
Maintenance	Hookshot upgrades, Redis, crypto store	Script only
Failure mode	Missed events if down	DB has everything, export retries
Edit/redaction capture	Real-time only	Retained in DB forever

Why This Is Better Than the Custom Bot (Original Phase 6)

The original Phase 6 plan proposed a full matrix-nio bot with E2EE, asyncpg, systemd service, healthchecks, and monitoring. That's ~500-1000 lines of Python for a problem that Synapse already solves with 2 config lines.

The custom bot approach is only justified if:

• Real-time alerting on specific messages is needed (not requested)
• Independent archive separate from Synapse DB is required (not requested)
• Synapse admin API is insufficient for export needs (it's not)

3. Questions Requiring Live Test

None. All claims are verified from Synapse source code:

• redaction_retention_period: null — confirmed in synapse/config/server.py
• msc2815_enabled — confirmed in synapse/config/experimental.py line 372
• Admin API event access — confirmed working (used throughout Phase 3-5)
• Hookshot E2EE+MAS blocker — confirmed from GitHub issues with reproduction steps

4. Estimated Effort

Synapse Config Change

• Edit homeserver.yaml: 5 minutes
• Restart Synapse: 1 minute
• Verify via admin API: 5 minutes
• Total: ~15 minutes

Export Script

• Python script to query admin API and write JSONL/markdown: 1-2 hours
• Cron setup: 5 minutes
• Test with existing rooms: 15 minutes
• Total: ~2 hours

Compare to Full Hookshot Deployment

• Deploy hookshot container: 30 min
• Debug E2EE+MAS incompatibility: hours of dead end
• Fall back to alternative: start over
• Total: wasted time

Compare to Custom Bot (Original Phase 6)

• Bot code + E2EE + DB schema + systemd + monitoring: 4-6 hours
• Device verification walkthrough: 30 min
• Export pipeline: 1-2 hours
• Total: 6-8 hours

5. Blockers

None for the recommended approach. The only blocker was hookshot's E2EE+MAS incompatibility, which the recommended approach avoids entirely.

6. Decision Matrix

Approach	Viable	Effort	Completeness	Ops Burden
Hookshot	NO (E2EE+MAS blocked)	N/A	N/A	N/A
Custom matrix-nio bot	Yes	High (6-8h)	Full (real-time + export)	Medium
Synapse retention + export	Yes	Low (~2h)	Full (DB + batch export)	Minimal

Recommendation: Synapse retention + export script.

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Ref Files Produced

1. .ref/synapse_retention_discovery.ref — Current retention config, MSC2815 support, DB sizes, growth rate, rollback
2. .ref/hookshot_deployment_discovery.ref — Contabo resources, port conflicts, compose snippet
3. .ref/hookshot_e2ee_discovery.ref — BLOCKER documented — E2EE+MAS incompatibility
4. .ref/hookshot_payload_discovery.ref — Webhook payload shape (for future reference)
5. .ref/hookshot_room_targeting_discovery.ref — Per-room model, no wildcard, current portals
6. .ref/archive_receiver_discovery.ref — Storage options, alternative approaches, CT recommendations
7. .ref/PHASE6_DECISION.md — This file