feat: add session persistence to CLI

- Add save-only endpoint (POST /conversations/{id}/save) for persisting
  messages without triggering agent execution
- Add sessions command to list previous conversation sessions
- Add --resume flag to chat command for resuming sessions by ID
- Buffer streamed responses and save after completion
- Update AGENTS.md with session commands and remove outdated limitation
- Add 3 new tests for save endpoint (208 total)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

webber-api/docs/COVERAGE.md

@@ -2,9 +2,9 @@
 
 > Tracking progress towards Claude Code-like functionality
 
-## Current Status: ~80% Complete
+## Current Status: ~85% Complete
 
-Last updated: 2026-01-11
+Last updated: 2026-01-14
 
 ---
 
@@ -122,11 +122,13 @@ Last updated: 2026-01-11
 |---------|----------|-------------|------------|
 | **Web search summarizer** | Tools | Agent to extract core content from web pages (remove nav, footers, etc.) and preserve relevant links for nested fetching | Medium |
 | **Tool result caching** | Infrastructure | Cache file reads for performance | Low |
-| **Session persistence** | CLI | Save/resume conversations | Medium |
+| ~~**Session persistence**~~ | CLI | ✅ Save/resume conversations via `sessions` and `chat --resume` | Medium |
 | **Todo tracking** | CLI | Built-in task list (`/todo`) | Medium |
 | **Git integration** | CLI | Auto-commit, branch management | Medium |
-| **Agent handoff** | Orchestration | Explore → Plan → Task workflow | High |
+| ~~**Agent handoff**~~ | Orchestration | ✅ Task agent is main agent, spawns Explore/Plan as needed (Claude Code pattern) | High |
 | ~~**Retry logic**~~ | Infrastructure | ✅ Auto-retry with exponential backoff | Low |
+| ~~**Permission modes**~~ | CLI | ✅ default/plan/auto_accept modes controlling tool access | Medium |
+| ~~**CLI shell features**~~ | CLI | ✅ prompt_toolkit: history, tab completion, auto-suggest | Low |
 
 ### Low Priority
 
@@ -149,14 +151,14 @@ Last updated: 2026-01-11
 | API tests | 11 | 11 | ✅ |
 | Plan agent tests | 15 | 15 | ✅ |
 | Task agent tests | 15 | 15 | ✅ |
-| Conversation tests | 19 | 19 | ✅ |
+| Conversation tests | 22 | 22 | ✅ |
 | Token tests | 6 | 6 | ✅ |
 | Retry tests | 29 | 29 | ✅ |
 | Security tests | 14 | 14 | ✅ |
 | Integration tests | 10 | 10 | ✅ Agent + real LLM |
 | E2E tests | 12 | 12 | ✅ Full API workflow |
 
-**Total: 205 tests passing**
+**Total: 208 tests passing**
 
 **Test breakdown:**
 - Read/Glob/Grep tools: 17 tests
@@ -167,7 +169,7 @@ Last updated: 2026-01-11
 - API endpoints: 11 tests
 - Plan agent: 15 tests
 - Task agent: 15 tests
-- Conversations: 19 tests
+- Conversations: 22 tests
 - Tokens: 6 tests
 - Retry: 29 tests
 - Security: 14 tests
@@ -224,9 +226,9 @@ cd webber-api && ./wakeup.sh
 
 # CLI commands (from webber-cli/)
 .venv/bin/webber-cli status                    # Check API connection
-.venv/bin/webber-cli explore "find tests"      # One-shot exploration
-.venv/bin/webber-cli explore "query" --no-stream  # Batch mode
-.venv/bin/webber-cli chat                      # Interactive mode
+.venv/bin/webber-cli chat                      # Interactive mode (Task agent, full tools)
+.venv/bin/webber-cli chat --mode plan          # Read-only mode (safe exploration)
+.venv/bin/webber-cli chat --mode auto_accept   # No approval prompts (use with caution)
 
 # API endpoints
 curl http://localhost:8095/health