diff --git a/README.md b/README.md
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+# AXON
+
+> A personal AI assistant with persistent, encrypted, semantically-searchable memory — built on a LangGraph supervisor agent, FastAPI, and Next.js.
+
+AXON is a full-stack AI assistant that goes beyond a stateless chatbot. It remembers what you tell it (encrypted at rest, PII-masked before embedding), can ingest your documents, summarise YouTube videos, and synthesise speech — all behind your own Supabase auth.
+
+---
+
+## ✨ Features
+
+- 💬 **Streaming chat** over Server-Sent Events with any model on [OpenRouter](https://openrouter.ai)
+- 🧠 **Encrypted long-term memory** with semantic search (pgvector + HNSW, cosine similarity)
+- 📄 **File ingestion** — upload `.txt`, `.md`, `.pdf`, `.docx`; auto-chunked and embedded
+- 📺 **YouTube agent** — paste a link, get a hierarchical LLM summary saved to your library
+- 🔊 **Text-to-speech** via OpenRouter, stored in a private Supabase bucket
+- 🔐 **Privacy by design** — Microsoft Presidio masks PII before embedding; Fernet (AES-128-CBC + HMAC) encrypts stored plaintext
+- 🚦 **Per-user rate limiting** with SlowAPI
+- 🔑 **Supabase Auth** (Google OAuth) with row-level security on every table
+
+---
+
+## 🏗️ Architecture
+
+```
+┌──────────────────┐         ┌──────────────────────────┐         ┌─────────────────┐
+│  Next.js 16      │  HTTPS  │  FastAPI + LangGraph     │  HTTPS  │  OpenRouter     │
+│  (App Router)    │ ──────► │  Supervisor Agent        │ ──────► │  LLMs / TTS /   │
+│  Server Functions│  SSE    │  + sub-agents            │         │  Embeddings     │
+└──────────────────┘         └──────────────────────────┘         └─────────────────┘
+         │                              │
+         │ JWT                          │ pgvector / Storage / RLS
+         ▼                              ▼
+┌────────────────────────────────────────────────────────┐
+│                Supabase (Postgres + Auth + Storage)    │
+└────────────────────────────────────────────────────────┘
+```
+
+### LangGraph supervisor
+
+```
+START → supervisor ──► memory_agent     → supervisor → END
+                  ──► youtube_agent    → supervisor → END
+                  ──► save_transcript  → supervisor → END
+                  ──► generate_tts     → supervisor → END
+                  ──► (direct reply) ─────────────────► END
+```
+
+The **supervisor** is a tool-calling LLM that decides whether to delegate. Sub-agents return `ToolMessage`s that feed back into a second supervisor pass which streams the final answer to the user.
+
+---
+
+## 🧱 Tech Stack
+
+### Backend (`backend/`)
+
+| Layer         | Tool                                        |
+| ------------- | ------------------------------------------- |
+| Framework     | FastAPI (async)                             |
+| Agents        | LangGraph + LangChain (supervisor pattern)  |
+| LLM gateway   | OpenRouter                                  |
+| Database      | Supabase Postgres + pgvector (HNSW)         |
+| Storage       | Supabase Storage (private `audio` bucket)   |
+| Auth          | Supabase JWT (HS256)                        |
+| Encryption    | Fernet (AES-128-CBC + HMAC-SHA256)          |
+| PII masking   | Microsoft Presidio + spaCy `en_core_web_sm` |
+| Rate limiting | SlowAPI                                     |
+| Package mgr   | [uv](https://github.com/astral-sh/uv)       |
+
+### Frontend (`frontend/`)
+
+| Layer         | Tool                               |
+| ------------- | ---------------------------------- |
+| Framework     | Next.js 16 (App Router, Turbopack) |
+| UI            | React 19 + Tailwind v4 + shadcn/ui |
+| Data fetching | TanStack Query v5                  |
+| Validation    | Zod v4                             |
+| SSE parsing   | `eventsource-parser`               |
+| Auth client   | `@supabase/ssr`                    |
+| Package mgr   | pnpm                               |
+
+---
+
+## 📂 Repository Layout
+
+```
+axon/
+├── backend/
+│   └── app/
+│       ├── agents/        # LangGraph orchestrator, supervisor, sub-agents
+│       ├── core/          # config, security, crypto, privacy, limiter
+│       ├── db/            # Supabase client + embeddings
+│       └── features/      # auth · chat · memory · models · youtube · audio
+├── frontend/
+│   ├── app/               # Next.js App Router (routing only)
+│   ├── features/          # audio · auth · chat · memory · youtube
+│   ├── components/ui/     # shadcn primitives
+│   └── lib/               # api client, Supabase server/client helpers
+└── supabase/
+    └── migrations/        # Schema, RLS, pgvector, RPCs
+```
+
+Both halves follow a **feature-based** architecture — each feature owns its router, service, schemas, components, and hooks.
+
+---
+
+## 🚀 Getting Started
+
+### Prerequisites
+
+- Python ≥ 3.10, [uv](https://github.com/astral-sh/uv)
+- Node.js ≥ 20, [pnpm](https://pnpm.io)
+- A [Supabase](https://supabase.com) project (free tier works)
+- An [OpenRouter](https://openrouter.ai) API key
+
+### 1. Supabase
+
+1. Create a project, copy the URL + anon key + service-role key.
+2. Run the migrations in `supabase/migrations/` (in order) via the SQL editor or the Supabase CLI.
+3. Enable Google OAuth and set the redirect URL.
+
+### 2. Backend
+
+```bash
+cd backend
+uv sync
+uv run python -m spacy download en_core_web_sm
+cp .env.example .env   # fill in keys
+uv run uvicorn app.main:app --reload
+```
+
+Open http://localhost:8000/docs for the OpenAPI explorer.
+
+### 3. Frontend
+
+```bash
+cd frontend
+pnpm install
+cp .env.example .env.local   # fill in Supabase + backend URL
+pnpm dev
+```
+
+Open http://localhost:3000.
+
+---
+
+## 🔑 Environment Variables (overview)
+
+**Backend** (`backend/.env`)
+
+```
+SUPABASE_URL=
+SUPABASE_ANON_KEY=
+SUPABASE_SERVICE_ROLE_KEY=
+SUPABASE_JWT_SECRET=
+OPENROUTER_API_KEY=
+ENCRYPTION_KEY=               # Fernet key (urlsafe base64, 32 bytes)
+EMBEDDING_MODEL=openai/text-embedding-3-large
+EMBEDDING_DIMENSIONS=1536
+```
+
+**Frontend** (`frontend/.env.local`)
+
+```
+NEXT_PUBLIC_SUPABASE_URL=
+NEXT_PUBLIC_SUPABASE_ANON_KEY=
+BACKEND_URL=http://localhost:8000
+```
+
+---
+
+## 🛡️ Security Notes
+
+- Embeddings are computed on **PII-masked** text; stored plaintext is **Fernet-encrypted**.
+- The user ID is **always derived from a validated JWT** server-side — never trusted from the client.
+- Every table has **row-level security** enforced in Postgres; the backend uses the service-role key but consistently filters by `user_id`.
+- Rate limits are keyed on the authenticated user (per-JWT), not IP.
+
+---
+
+## 📋 API Surface (selected)
+
+| Method | Path                         | Notes                           |
+| ------ | ---------------------------- | ------------------------------- |
+| GET    | `/api/v1/health`             | Liveness, public                |
+| GET    | `/api/v1/auth/me`            | JWT-protected user info         |
+| GET    | `/api/v1/models`             | Cached OpenRouter catalogue     |
+| POST   | `/api/v1/chat/stream`        | SSE stream from the agent       |
+| GET    | `/api/v1/chat/conversations` | List conversations              |
+| POST   | `/api/v1/memory` · `/search` | CRUD + semantic search          |
+| POST   | `/api/v1/memory/upload`      | Multipart file ingestion        |
+| GET    | `/api/v1/youtube`            | Saved YouTube video transcripts |
+
+See `backend/BACKEND.md` for the full reference.
+
+---
+
+## 📜 License
+
+This is a personal project. No license granted; all rights reserved by the author.
diff --git a/frontend/lib/api.ts b/frontend/lib/api.ts
index 4e32ba3..5204b37 100644
--- a/frontend/lib/api.ts
+++ b/frontend/lib/api.ts
@@ -250,10 +250,13 @@ export function renameAudioEntry(
     id,
     title,
   });
-  return apiFetch<AudioEntryOut>(`/api/v1/audio/${encodeURIComponent(validId)}`, {
-    method: 'PATCH',
-    body: JSON.stringify({ title: validTitle }),
-  });
+  return apiFetch<AudioEntryOut>(
+    `/api/v1/audio/${encodeURIComponent(validId)}`,
+    {
+      method: 'PATCH',
+      body: JSON.stringify({ title: validTitle }),
+    },
+  );
 }
 
 export function deleteAudioEntry(id: string): Promise<void> {
diff --git a/implementationPlan.MD b/implementationPlan.MD
index f42ff77..21ff9fd 100644
--- a/implementationPlan.MD
+++ b/implementationPlan.MD
@@ -548,6 +548,150 @@ User: "yes"
 
 ---
 
+## PHASE 11 — Deep Search Agent
+
+> **Architecture decision log:**
+>
+> - **Search provider:** Tavily API — purpose-built for LLM/agent workflows; `search_depth="advanced"` returns full page content (not just snippets), structured results, and optionally a pre-generated answer. Free tier: 1 000 searches/month. Uses its own `TAVILY_API_KEY` — existing `OPENROUTER_API_KEY` unchanged.
+> - **Agent pattern:** Same supervisor handoff as YouTube — `transfer_to_deepsearch_agent` → `deepsearch_agent_node` → supervisor. No new graph topology needed.
+> - **Save flow:** After presenting results, supervisor asks "Want to save this research?" → user confirms → `save_deep_search` tool node → INSERT into `deep_searches` table + embed `query + summary` → INSERT into `memory_entries` (so memory_agent can recall it in future conversations).
+> - **Delete:** Must remove from BOTH `deep_searches` table AND the corresponding `memory_entries` row. `memory_entry_id` FK stored directly in the row (cleaner than pattern-matching).
+> - **Edit:** `title` change — free (no re-embed). `summary` change — re-embed → update `memory_entries.embedding` in place.
+
+### Overall flow
+
+```text
+User: "deep search quantum computing breakthroughs 2025"
+  → supervisor detects research intent → calls transfer_to_deepsearch_agent
+  → deepsearch_agent:
+      1. Extract query from last HumanMessage
+      2. TavilyClient.search(query, search_depth="advanced", max_results=10) via asyncio.to_thread
+      3. Build synthesis context (each result capped at 2000 chars, total 20 000)
+      4. LLM call → synthesize summary + key_findings: list[str]
+      5. Build sources: [{title, url, snippet: content[:300]}]
+      6. Store JSON in state["deepsearch_context"]; return ToolMessage
+  → supervisor: presents summary + key findings + numbered source list
+                asks "Want me to save this research?"
+
+User: "yes"
+  → supervisor calls save_deep_search()
+  → save_deep_search node:
+      INSERT deep_searches; embed(query + "\n\n" + summary) → INSERT memory_entries
+      UPDATE deep_searches.memory_entry_id = <new_id>
+  → supervisor: "Research saved ✓ — also indexed in your memory for future recall"
+
+User later: "what did I find about quantum computing?"
+  → memory_agent → vector search → returns saved summary
+```
+
+---
+
+### 11A — Dependencies + Config
+
+- [ ] `uv add tavily-python` — official Tavily Python client
+- [ ] `app/core/config.py`: add `tavily_api_key: str` + `deepsearch_model: str = "google/gemini-2.5-flash"` + `deepsearch_max_results: int = 10`
+- [ ] `backend/.env.example`: add `TAVILY_API_KEY=`
+
+### 11B — Database (`supabase/migrations/`)
+
+- [ ] New migration: create `deep_searches` table:
+  ```sql
+  CREATE TABLE public.deep_searches (
+      id               UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+      user_id          UUID        NOT NULL REFERENCES auth.users(id) ON DELETE CASCADE,
+      query            TEXT        NOT NULL,
+      title            TEXT        NOT NULL,          -- editable; defaults to query
+      summary          TEXT        NOT NULL,          -- AI-synthesized answer
+      key_findings     JSONB       NOT NULL DEFAULT '[]', -- string[]
+      sources          JSONB       NOT NULL DEFAULT '[]', -- [{title, url, snippet}]
+      memory_entry_id  UUID        REFERENCES memory_entries(id) ON DELETE SET NULL,
+      created_at       TIMESTAMPTZ NOT NULL DEFAULT now()
+  );
+  CREATE INDEX deep_searches_user_created_idx
+      ON public.deep_searches (user_id, created_at DESC);
+  ```
+- [ ] RLS: `user_id = (select auth.uid())` on SELECT / INSERT / DELETE / UPDATE — subquery form (same pattern as all other tables)
+- [ ] `memory_entry_id ON DELETE SET NULL` — deep search row survives if memory entry is independently cleaned up
+
+### 11C — Backend feature layer (`app/features/deepsearch/`)
+
+- [ ] `__init__.py`
+- [ ] `schemas.py`: `SourceItem(title, url, snippet)` · `DeepSearchOut(id, query, title, summary, key_findings, sources, created_at)` · `DeepSearchCreate(query, title: str = Field(..., max_length=200), summary: str = Field(..., max_length=10000), key_findings, sources)` · `DeepSearchPatch(title: str | None = Field(None, max_length=200), summary: str | None = Field(None, max_length=10000))` with `model_validator` requiring at least one field; service layer must accept these schemas for create/update so direct API calls cannot bypass the limits
+- [ ] `service.py`:
+  - `save_deep_search(user_id, payload: dict) -> DeepSearchOut` — INSERT row; attempt embed `f"[Deep Search] {query}: {summary}"` → INSERT `memory_entries` → UPDATE row with `memory_entry_id`; if embedding or `memory_entries` INSERT fails, log the error with context (deep_search id, query, exception) and continue with `memory_entry_id = NULL` (non-fatal, same resilience pattern as YouTube)
+  - `list_deep_searches(user_id, limit=50, offset=0) -> list[DeepSearchOut]` — ordered by `created_at DESC`
+  - `get_deep_search(id, user_id) -> DeepSearchOut | None`
+  - `delete_deep_search(id, user_id) -> bool` — fetch `memory_entry_id` → `delete_memory()` if set → DELETE row
+  - `update_deep_search(id, user_id, patch) -> DeepSearchOut | None` — if `summary` changed: re-embed → update `memory_entries.embedding`; if `memory_entry_id` is NULL attempt to create a new memory entry and set it; if that fails log and keep the row updated without `memory_entry_id`; UPDATE row; all log messages must reference `update_deep_search` and include `memory_entry_id` context
+- [ ] `router.py`:
+  - `GET    /api/v1/deepsearch` — list paginated; `@limiter.limit("60/minute")`
+  - `GET    /api/v1/deepsearch/{id}` — single; `@limiter.limit("60/minute")`
+  - `DELETE /api/v1/deepsearch/{id}` — 204; `@limiter.limit("30/minute")`
+  - `PATCH  /api/v1/deepsearch/{id}` — edit title/summary; `@limiter.limit("30/minute")`
+
+### 11D — Agent subagent (`app/agents/subagents/deepsearch_agent.py`)
+
+- [ ] `deepsearch_agent_node(state: AxonState) -> dict`:
+  1. Extract query from last `HumanMessage` (strip intent phrases: "deep search", "research", "find out about")
+  2. `asyncio.to_thread(TavilyClient(api_key=settings.tavily_api_key).search, query, search_depth="advanced", max_results=settings.deepsearch_max_results)`
+  3. Build synthesis context: each result capped at 2 000 chars; total cap 20 000 chars
+  4. LLM call (`settings.deepsearch_model` via OpenRouter) → `summary` + `key_findings: list[str]`
+  5. Build `sources`: `[{title, url, snippet: content[:300]}]`
+  6. Validate with Pydantic `DeepSearchPayload`; fallback to raw concat on parse error
+  7. Store JSON in `state["deepsearch_context"]`; return ToolMessage closing handoff tool call
+- [ ] Error handling:
+  - `TavilyAPIError` / network errors → log internally, return descriptive error ToolMessage; never expose raw API errors or tracebacks
+  - LLM synthesis call (`settings.deepsearch_model` via OpenRouter): wrap in `try/except`; catch timeouts, rate-limit errors, and HTTP errors; apply exponential backoff with 2 retries; on persistent failure return a descriptive error ToolMessage without raw exception details
+  - Malformed/unparseable LLM response (including `JSONDecodeError`): log internally; fall back to raw concatenation strategy (step 6) instead of crashing
+  - All internal exceptions must be logged with context (query, model) but must NOT be leaked to the returned ToolMessage
+
+### 11E — Save tool (`app/features/deepsearch/tool.py`)
+
+- [ ] `save_deep_search_node(state: AxonState) -> dict` — LangGraph node (same pattern as `save_transcript_node`):
+  - Read + parse `state["deepsearch_context"]`; validate required fields
+  - Call `deepsearch_service.save_deep_search(user_id, payload)`
+  - Return confirmation ToolMessage; clear `state["deepsearch_context"]`
+- [ ] `save_deep_search` stub `@tool` (body never executes)
+
+### 11F — State + Supervisor + Orchestrator wiring
+
+- [ ] `app/agents/state.py`: add `deepsearch_context: str` (empty string default)
+- [ ] `app/agents/supervisor.py`:
+  - Add `transfer_to_deepsearch_agent` + `save_deep_search` stubs to `bind_tools`
+  - System prompt: trigger phrases → `transfer_to_deepsearch_agent`; after ToolMessage present summary + ask to save; on confirmation call `save_deep_search`; do NOT re-call agent if `deepsearch_context` already populated
+- [ ] `app/agents/orchestrator.py`: add `deepsearch_agent` node + `save_deep_search_node`; extend `_should_continue` routing; add edge `deepsearch_agent → supervisor`
+- [ ] Mount deepsearch router in `app/main.py`
+
+### 11G — Frontend Deep Search Library (`features/deepsearch/`)
+
+- [ ] `features/deepsearch/types.ts` — `SourceItem`, `DeepSearchOut`
+- [ ] `features/deepsearch/hooks/useDeepSearch.ts` — `useDeepSearches()` (user-scoped key `['deep-searches', userId]`) · `useDeleteDeepSearch()` · `useUpdateDeepSearch()` (optimistic title)
+- [ ] `features/deepsearch/components/DeepSearchCard.tsx`:
+  - Inline-editable title (`useOptimistic` — same pattern as `AudioCard`)
+  - Summary: `line-clamp-4` + expand/collapse (same pattern as `VideoTranscriptCard`)
+  - Summary edit mode: click → textarea → Save/Cancel → `useUpdateDeepSearch` (re-embed server-side on summary change)
+  - Key findings: bullet list, first 4 visible + expand
+  - Sources: collapsed accordion ("N sources") → numbered `<a target="_blank">` links
+  - Delete dialog: warns that the linked memory entry will also be removed
+- [ ] `features/deepsearch/components/DeepSearchLibrary.tsx` — grid, skeleton, empty state
+- [ ] `app/(dashboard)/deepsearch/page.tsx` — back-to-chat header
+- [ ] `features/chat/components/ChatWindow.tsx` — add `Search` icon link to `/deepsearch` in toolbar
+- [ ] `lib/api.ts`: `listDeepSearches()` · `deleteDeepSearch(id)` (Zod UUID) · `updateDeepSearch(id, patch)` (Zod: title max 200, summary max 10 000, at least one field)
+
+### 11H — Verification
+
+- [ ] "deep search latest AI models 2025" → deepsearch_agent calls Tavily → summary + key findings + sources in chat
+- [ ] "yes save it" → `save_deep_search` called → entry visible in `GET /api/v1/deepsearch`
+- [ ] `/deepsearch` page → cards with summary, findings, collapsible source links
+- [ ] Edit title → optimistic update → persisted
+- [ ] Edit summary → `PATCH` → re-embed triggered → memory_agent finds updated content in future chat
+- [ ] Delete → row removed from `deep_searches` + `memory_entries` → UI updates
+- [ ] Future chat "what did I research?" → memory_agent returns saved summary
+- [ ] Tavily 429/down → graceful error message, no crash
+- [ ] `PATCH` with empty body → 422
+
+---
+
 ## End-to-End Verification Checklist
 
 - [ ] Google OAuth → JWT validated on `/api/v1/auth/me` → 200