fix: capture subagent parent edges end-to-end

[upsetbit]

Problem

The panel never grouped subagent sessions under their parents, and Insights → Subagents was always empty. The production Postgres had 0 parent edges across 3,570 sessions, while local stores were capturing them fine (226 on one device alone). Two independent bugs broke the pipeline:

1. Push dropped the edge. sessionToProto never mapped Session.ParentSessionID onto the wire, so every edge the importers captured (codex thread spawns, hermes parents) died at sync time. This is what made already-linked codex children — e.g. fact-check fan-outs — show up flat in the panel.
2. Claude Code subagents were never imported. The walker expected agent-<uuid>.jsonl, but real CLIs write agent-<17 hex>.jsonl, and Workflow-tool spawns nest deeper at subagents/workflows/wf_<id>/. Worse: every record in a subagent transcript carries the parent's sessionId, so adopting it (as the parser did) would clobber the parent row on upsert.

Fix

• sessionToProto maps ParentSessionID → parent_session_id (the proto field and the server upsert already existed).
• The walker accepts both subagent namings and the workflow nesting; the child's identity is the filename stem (agent-<id>), never the embedded sessionId; the parent UUID is the directory above the innermost subagents component.
• ProjectionVersion 10→11 so sync_reconcile re-pushes existing rows and the server learns the edges retroactively.
• Docs updated to describe the real layouts and the v10/v11 projection rows.

Validation

• Full suite (just test-race), golangci-lint, gen-check, tidy-check, lint-md all green.
• New table-driven tests pin identity + edge recovery for every observed layout (Agent tool, Workflow tool, old UUID naming, degraded non-UUID parents).
• Sandboxed sync over real ~/.claude/projects data: claude-code went from 0 to 251/315 sessions linked as children (including a 145-child workflow fan-out), codex 196, hermes 31, zero orphan edges, parents intact.

After release: run prosa sync on each device — reconcile re-pushes and the panel grouping + Subagents insight light up for historical data too.

🤖 Generated with Claude Code

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