docs(adr): add 0007-claude-question-channel-design

docs/adr/0007-claude-question-channel-design.md

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+---
+status: accepted
+date: 2026-05-03
+decision-makers: [janpetervisser]
+---
+
+# ADR-0007: Agent ↔ user question channel via persistent table + LISTEN/NOTIFY
+
+## Context and Problem Statement
+
+When Claude Code is executing a task and needs human input, it must be able to pause, post a question, and receive an answer — potentially across separate sessions. The app must notify an active user that a question is waiting. How should this async communication channel be designed?
+
+## Decision Drivers
+
+- Questions must survive agent session restarts (persistent, not in-memory).
+- The app user needs a real-time notification without polling from the client.
+- The infrastructure already includes PostgreSQL with LISTEN/NOTIFY (used for M8 realtime updates).
+- Answers must be readable by the agent in a future session without the original connection.
+
+## Considered Options
+
+- **Synchronous polling only** — agent polls an endpoint every N seconds.
+- **Push via SSE without persistence** — agent opens SSE connection, user pushes answer over it.
+- **Persistent `claude_questions` table + PostgreSQL LISTEN/NOTIFY**
+
+## Decision Outcome
+
+Chosen option: **Persistent table + LISTEN/NOTIFY**, because it is the only option that survives session restarts on both ends and reuses existing infrastructure.
+
+### Consequences
+
+- Good, because questions survive agent and user session restarts.
+- Good, because reuses the `scrum4me_changes` LISTEN/NOTIFY channel already in place.
+- Good, because any product member with access can answer, not just the original session.
+- Bad, because adds a `claude_questions` table and trigger to the schema.
+- Bad, because LISTEN/NOTIFY requires a persistent DB connection (`DIRECT_URL` env var).
+
+### Confirmation
+
+`docs/patterns/claude-question-channel.md` documents the full implementation. MCP tools: `ask_user_question`, `get_question_answer`, `list_open_questions`, `cancel_question`.
+
+## Pros and Cons of the Options
+
+### Synchronous polling only
+
+- Good, because simple — no extra infrastructure.
+- Bad, because agent blocks a CPU slot while polling; question lost if agent restarts.
+- Bad, because no real-time notification to the user.
+
+### Push via SSE without persistence
+
+- Good, because low latency.
+- Bad, because agent-side SSE connection is fragile across restarts.
+- Bad, because no persistence — if the user isn't connected at the moment the question is posted, it is lost.
+
+### Persistent table + LISTEN/NOTIFY
+
+- Good, because fully durable.
+- Good, because real-time notification to the user reuses existing M8 infrastructure.
+- Neutral, because requires `DIRECT_URL` for a persistent PostgreSQL connection (already required for M8).
+
+## More Information
+
+See `docs/plans/M11-claude-questions.md` and `docs/patterns/claude-question-channel.md`.