feat: replace namespace permissions with per-node graph permission model (can_read/can_create_rel/can_write/has_ownership)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project
+
+Axolotl (`ax`) is a CLI-native issue tracker built in Go, using a local SQLite file (`.ax.db`) as its database. It's designed for use by individuals and AI agents, with JSON output support for machine integration.
+
+## Commands
+
+```bash
+go build -o ax .        # Build the binary
+go test ./...           # Run all tests (e2e_test.go covers most functionality)
+go test -run TestName . # Run a single test by name
+```
+
+## Architecture
+
+The codebase has four distinct layers:
+
+### 1. `cmd/` — CLI layer (Cobra)
+Parses flags into typed input structs and calls the service layer. `root.go` handles alias expansion (including `$me`, `$@`, `$1`-`$N` variable substitution) and wires up the `NodeService`.
+
+### 2. `service/` — Business logic
+`NodeService` is the central interface (`service/node_service.go`). The implementation (`node_service_impl.go`) enforces:
+- Permission model via `getPermContext()` — BFS from the user's own node following permission rels
+- Blocker validation (can't close an issue with open blockers)
+- `@mention` extraction → automatic edge creation
+- Single-value relation enforcement (`assignee`, `in_namespace`)
+- Auto-creation of referenced user/namespace nodes
+
+### 3. `store/` — Persistence
+`Store` interface wraps SQLite with graph primitives: nodes, tags, and typed directed edges. Schema is 3 tables (`nodes`, `tags`, `rels`). All multi-step ops use `store.Transaction()`.
+
+### 4. `output/` — Presentation
+Handles both colored terminal output and JSON serialization. Applies sort order: open → due → done, high → medium → low priority.
+
+## Core Data Model
+
+**Node**: a graph node with a 5-char ID, title, content, `Tags []string`, and `Relations map[string][]string`.
+
+**Property tags** use the `_key::value` pattern: `_type::issue|note|user|namespace`, `_status::open|done`, `_prio::high|medium|low`.
+
+**Relation types** (`models/rel_type.go`): `blocks`, `subtask`, `related`, `assignee` (single-value), `in_namespace` (single-value), `created`, `mentions`, `can_read`, `can_create_rel`, `can_write`, `has_ownership`.
+
+**Permission model**: Four inclusive levels (1–4). Transitive via BFS from user's self-owned node. `can_read`=1, `can_create_rel`=2, `can_write`=3, `has_ownership`=4. Creator auto-gets `has_ownership` on every new node. Users self-own. Deleting a node cascades to all nodes it owns. User/namespace nodes are globally readable.
+
+## Config
+
+The CLI searches upward from CWD for `.axconfig` (like git), falling back to `~/.config/ax/config.json`. The `AX_USER` env var overrides the configured username. The database file `.ax.db` is similarly discovered by walking upward.