diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/__init__.py b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/agent.py b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/agent.py
new file mode 100644
index 000000000..2d231e383
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/agent.py
@@ -0,0 +1,54 @@
+"""`memory` route: ``SubAgent`` spec for deepagents."""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+from typing import Any
+
+from deepagents import SubAgent
+from langchain_core.language_models import BaseChatModel
+
+from app.agents.multi_agent_with_deepagents.subagents.shared.md_file_reader import (
+    read_md_file,
+)
+from app.agents.multi_agent_with_deepagents.subagents.shared.permissions import (
+    ToolsPermissions,
+    merge_tools_permissions,
+)
+from app.agents.multi_agent_with_deepagents.subagents.shared.subagent_builder import (
+    pack_subagent,
+)
+
+from .tools.index import load_tools
+
+NAME = "memory"
+
+
+def build_subagent(
+    *,
+    dependencies: dict[str, Any],
+    model: BaseChatModel | None = None,
+    extra_middleware: Sequence[Any] | None = None,
+    extra_tools_bucket: ToolsPermissions | None = None,
+) -> SubAgent:
+    buckets = load_tools(dependencies=dependencies)
+    merged_tools_bucket = merge_tools_permissions(buckets, extra_tools_bucket)
+    tools = [
+        row["tool"]
+        for row in (*merged_tools_bucket["allow"], *merged_tools_bucket["ask"])
+        if row.get("tool") is not None
+    ]
+    interrupt_on = {r["name"]: True for r in merged_tools_bucket["ask"] if r.get("name")}
+    description = read_md_file(__package__, "description").strip()
+    if not description:
+        description = "Handles memory tasks for this workspace."
+    system_prompt = read_md_file(__package__, "system_prompt").strip()
+    return pack_subagent(
+        name=NAME,
+        description=description,
+        system_prompt=system_prompt,
+        tools=tools,
+        interrupt_on=interrupt_on,
+        model=model,
+        extra_middleware=extra_middleware,
+    )
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/description.md b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/description.md
new file mode 100644
index 000000000..4c2cdcd0e
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/description.md
@@ -0,0 +1 @@
+Use for storing durable user memory (private team variant selected at runtime).
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/system_prompt.md b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/system_prompt.md
new file mode 100644
index 000000000..32becf233
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/system_prompt.md
@@ -0,0 +1,56 @@
+You are the SurfSense memory operations sub-agent.
+You receive delegated instructions from a supervisor agent and return structured results for supervisor synthesis.
+
+<goal>
+Persist durable preferences/facts/instructions with `update_memory` while avoiding transient or unsafe storage.
+</goal>
+
+<visibility_scope>
+{{MEMORY_VISIBILITY_POLICY}}
+</visibility_scope>
+
+<available_tools>
+- `update_memory`
+</available_tools>
+
+<tool_policy>
+- Save only durable information with future value.
+- Do not store transient chatter.
+- Do not store secrets unless explicitly instructed.
+- If memory intent is unclear, return `status=blocked` with the missing intent signal.
+</tool_policy>
+
+<out_of_scope>
+- Do not execute non-memory tool actions.
+- Do not store irrelevant, transient, or speculative information.
+</out_of_scope>
+
+<safety>
+- Prefer minimal-memory writes over over-collection.
+- Never claim memory was updated unless `update_memory` succeeded.
+</safety>
+
+<failure_policy>
+- On tool failure, return `status=error` with concise recovery steps.
+- When intent is ambiguous, return `status=blocked` with required disambiguation fields.
+</failure_policy>
+
+<output_contract>
+Return **only** one JSON object (no markdown/prose):
+{
+  "status": "success" | "partial" | "blocked" | "error",
+  "action_summary": string,
+  "evidence": {
+    "memory_updated": boolean,
+    "memory_category": "preference" | "fact" | "instruction" | null,
+    "stored_summary": string | null
+  },
+  "next_step": string | null,
+  "missing_fields": string[] | null,
+  "assumptions": string[] | null
+}
+Rules:
+- `status=success` -> `next_step=null`, `missing_fields=null`.
+- `status=partial|blocked|error` -> `next_step` must be non-null.
+- `status=blocked` due to missing required inputs -> `missing_fields` must be non-null.
+</output_contract>
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/__init__.py b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/__init__.py
new file mode 100644
index 000000000..0441a8cb4
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/__init__.py
@@ -0,0 +1,8 @@
+"""Memory tools: persist user or team markdown memory for later turns."""
+
+from .update_memory import create_update_memory_tool, create_update_team_memory_tool
+
+__all__ = [
+    "create_update_memory_tool",
+    "create_update_team_memory_tool",
+]
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/index.py b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/index.py
new file mode 100644
index 000000000..71d66d15f
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/index.py
@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from typing import Any
+
+from app.agents.multi_agent_with_deepagents.subagents.shared.permissions import (
+    ToolsPermissions,
+)
+from app.db import ChatVisibility
+
+from .update_memory import create_update_memory_tool, create_update_team_memory_tool
+
+
+def load_tools(*, dependencies: dict[str, Any] | None = None, **kwargs: Any) -> ToolsPermissions:
+    resolved_dependencies = {**(dependencies or {}), **kwargs}
+    if resolved_dependencies.get("thread_visibility") == ChatVisibility.SEARCH_SPACE:
+        mem = create_update_team_memory_tool(
+            search_space_id=resolved_dependencies["search_space_id"],
+            db_session=resolved_dependencies["db_session"],
+            llm=resolved_dependencies.get("llm"),
+        )
+        return {"allow": [{"name": getattr(mem, "name", "") or "", "tool": mem}], "ask": []}
+    mem = create_update_memory_tool(
+        user_id=resolved_dependencies["user_id"],
+        db_session=resolved_dependencies["db_session"],
+        llm=resolved_dependencies.get("llm"),
+    )
+    return {"allow": [{"name": getattr(mem, "name", "") or "", "tool": mem}], "ask": []}
diff --git a/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/update_memory.py b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/update_memory.py
new file mode 100644
index 000000000..23375a081
--- /dev/null
+++ b/surfsense_backend/app/agents/multi_agent_with_deepagents/subagents/builtins/memory/tools/update_memory.py
@@ -0,0 +1,375 @@
+"""Overwrite one markdown memory document per user or team, with size and shrink guards."""
+
+from __future__ import annotations
+
+import logging
+import re
+from typing import Any, Literal
+from uuid import UUID
+
+from langchain_core.messages import HumanMessage
+from langchain_core.tools import tool
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.db import SearchSpace, User
+
+logger = logging.getLogger(__name__)
+
+MEMORY_SOFT_LIMIT = 18_000
+MEMORY_HARD_LIMIT = 25_000
+
+_SECTION_HEADING_RE = re.compile(r"^##\s+(.+)$", re.MULTILINE)
+_HEADING_NORMALIZE_RE = re.compile(r"\s+")
+
+_MARKER_RE = re.compile(r"\[(fact|pref|instr)\]")
+_BULLET_FORMAT_RE = re.compile(r"^- \(\d{4}-\d{2}-\d{2}\) \[(fact|pref|instr)\] .+$")
+_PERSONAL_ONLY_MARKERS = {"pref", "instr"}
+
+
+# ---------------------------------------------------------------------------
+# Diff validation
+# ---------------------------------------------------------------------------
+
+
+def _extract_headings(memory: str) -> set[str]:
+    """Return all ``## …`` heading texts (without the ``## `` prefix)."""
+    return set(_SECTION_HEADING_RE.findall(memory))
+
+
+def _normalize_heading(heading: str) -> str:
+    """Normalize heading text for robust scope checks."""
+    return _HEADING_NORMALIZE_RE.sub(" ", heading.strip().lower())
+
+
+def _validate_memory_scope(
+    content: str, scope: Literal["user", "team"]
+) -> dict[str, Any] | None:
+    """Reject personal-only markers ([pref], [instr]) in team memory."""
+    if scope != "team":
+        return None
+
+    markers = set(_MARKER_RE.findall(content))
+    leaked = sorted(markers & _PERSONAL_ONLY_MARKERS)
+    if leaked:
+        tags = ", ".join(f"[{m}]" for m in leaked)
+        return {
+            "status": "error",
+            "message": (
+                f"Team memory cannot include personal markers: {tags}. "
+                "Use [fact] only in team memory."
+            ),
+        }
+    return None
+
+
+def _validate_bullet_format(content: str) -> list[str]:
+    """Return warnings for bullet lines that don't match the required format.
+
+    Expected: ``- (YYYY-MM-DD) [fact|pref|instr] text``
+    """
+    warnings: list[str] = []
+    for line in content.splitlines():
+        stripped = line.strip()
+        if not stripped.startswith("- "):
+            continue
+        if not _BULLET_FORMAT_RE.match(stripped):
+            short = stripped[:80] + ("..." if len(stripped) > 80 else "")
+            warnings.append(f"Malformed bullet: {short}")
+    return warnings
+
+
+def _validate_diff(old_memory: str | None, new_memory: str) -> list[str]:
+    """Return a list of warning strings about suspicious changes."""
+    if not old_memory:
+        return []
+
+    warnings: list[str] = []
+    old_headings = _extract_headings(old_memory)
+    new_headings = _extract_headings(new_memory)
+    dropped = old_headings - new_headings
+    if dropped:
+        names = ", ".join(sorted(dropped))
+        warnings.append(
+            f"Sections removed: {names}. "
+            "If unintentional, the user can restore from the settings page."
+        )
+
+    old_len = len(old_memory)
+    new_len = len(new_memory)
+    if old_len > 0 and new_len < old_len * 0.4:
+        warnings.append(
+            f"Memory shrank significantly ({old_len:,} -> {new_len:,} chars). "
+            "Possible data loss."
+        )
+    return warnings
+
+
+# ---------------------------------------------------------------------------
+# Size validation & soft warning
+# ---------------------------------------------------------------------------
+
+
+def _validate_memory_size(content: str) -> dict[str, Any] | None:
+    """Return an error/warning dict if *content* is too large, else None."""
+    length = len(content)
+    if length > MEMORY_HARD_LIMIT:
+        return {
+            "status": "error",
+            "message": (
+                f"Memory exceeds {MEMORY_HARD_LIMIT:,} character limit "
+                f"({length:,} chars). Consolidate by merging related items, "
+                "removing outdated entries, and shortening descriptions. "
+                "Then call update_memory again."
+            ),
+        }
+    return None
+
+
+def _soft_warning(content: str) -> str | None:
+    """Return a warning string if content exceeds the soft limit."""
+    length = len(content)
+    if length > MEMORY_SOFT_LIMIT:
+        return (
+            f"Memory is at {length:,}/{MEMORY_HARD_LIMIT:,} characters. "
+            "Consolidate by merging related items and removing less important "
+            "entries on your next update."
+        )
+    return None
+
+
+# ---------------------------------------------------------------------------
+# Forced rewrite when memory exceeds the hard limit
+# ---------------------------------------------------------------------------
+
+_FORCED_REWRITE_PROMPT = """\
+You are a memory curator. The following memory document exceeds the character \
+limit and must be shortened.
+
+RULES:
+1. Rewrite the document to be under {target} characters.
+2. Preserve existing ## headings. Every entry must remain under a heading. You may merge
+   or rename headings to consolidate, but keep names personal and descriptive.
+3. Priority for keeping content: [instr] > [pref] > [fact].
+4. Merge duplicate entries, remove outdated entries, shorten verbose descriptions.
+5. Every bullet MUST have format: - (YYYY-MM-DD) [fact|pref|instr] text
+6. Preserve the user's first name in entries — do not replace it with "the user".
+7. Output ONLY the consolidated markdown — no explanations, no wrapping.
+
+<memory_document>
+{content}
+</memory_document>"""
+
+
+async def _forced_rewrite(content: str, llm: Any) -> str | None:
+    """Use a focused LLM call to compress *content* under the hard limit.
+
+    Returns the rewritten string, or ``None`` if the call fails.
+    """
+    try:
+        prompt = _FORCED_REWRITE_PROMPT.format(
+            target=MEMORY_HARD_LIMIT, content=content
+        )
+        response = await llm.ainvoke(
+            [HumanMessage(content=prompt)],
+            config={"tags": ["surfsense:internal"]},
+        )
+        text = (
+            response.content
+            if isinstance(response.content, str)
+            else str(response.content)
+        )
+        return text.strip()
+    except Exception:
+        logger.exception("Forced rewrite LLM call failed")
+        return None
+
+
+# ---------------------------------------------------------------------------
+# Shared save-and-respond logic
+# ---------------------------------------------------------------------------
+
+
+async def _save_memory(
+    *,
+    updated_memory: str,
+    old_memory: str | None,
+    llm: Any | None,
+    apply_fn,
+    commit_fn,
+    rollback_fn,
+    label: str,
+    scope: Literal["user", "team"],
+) -> dict[str, Any]:
+    """Validate, optionally force-rewrite if over the hard limit, save, and
+    return a response dict.
+
+    Parameters
+    ----------
+    updated_memory : str
+        The new document the agent submitted.
+    old_memory : str | None
+        The previously persisted document (for diff checks).
+    llm : Any | None
+        LLM instance for forced rewrite (may be ``None``).
+    apply_fn : callable(str) -> None
+        Callback that sets the new memory on the ORM object.
+    commit_fn : coroutine
+        ``session.commit``.
+    rollback_fn : coroutine
+        ``session.rollback``.
+    label : str
+        Human label for log messages (e.g. "user memory", "team memory").
+    """
+    content = updated_memory
+
+    # --- forced rewrite if over the hard limit ---
+    if len(content) > MEMORY_HARD_LIMIT and llm is not None:
+        rewritten = await _forced_rewrite(content, llm)
+        if rewritten is not None and len(rewritten) < len(content):
+            content = rewritten
+
+    # --- hard-limit gate (reject if still too large after rewrite) ---
+    size_err = _validate_memory_size(content)
+    if size_err:
+        return size_err
+
+    scope_err = _validate_memory_scope(content, scope)
+    if scope_err:
+        return scope_err
+
+    # --- persist ---
+    try:
+        apply_fn(content)
+        await commit_fn()
+    except Exception as e:
+        logger.exception("Failed to update %s: %s", label, e)
+        await rollback_fn()
+        return {"status": "error", "message": f"Failed to update {label}: {e}"}
+
+    # --- build response ---
+    resp: dict[str, Any] = {
+        "status": "saved",
+        "message": f"{label.capitalize()} updated.",
+    }
+
+    if content is not updated_memory:
+        resp["notice"] = "Memory was automatically rewritten to fit within limits."
+
+    diff_warnings = _validate_diff(old_memory, content)
+    if diff_warnings:
+        resp["diff_warnings"] = diff_warnings
+
+    format_warnings = _validate_bullet_format(content)
+    if format_warnings:
+        resp["format_warnings"] = format_warnings
+
+    warning = _soft_warning(content)
+    if warning:
+        resp["warning"] = warning
+
+    return resp
+
+
+# ---------------------------------------------------------------------------
+# Tool factories
+# ---------------------------------------------------------------------------
+
+
+def create_update_memory_tool(
+    user_id: str | UUID,
+    db_session: AsyncSession,
+    llm: Any | None = None,
+):
+    uid = UUID(user_id) if isinstance(user_id, str) else user_id
+
+    @tool
+    async def update_memory(updated_memory: str) -> dict[str, Any]:
+        """Update the user's personal memory document.
+
+        Your current memory is shown in <user_memory> in the system prompt.
+        When the user shares important long-term information (preferences,
+        facts, instructions, context), rewrite the memory document to include
+        the new information.  Merge new facts with existing ones, update
+        contradictions, remove outdated entries, and keep it concise.
+
+        Args:
+            updated_memory: The FULL updated markdown document (not a diff).
+        """
+        try:
+            result = await db_session.execute(select(User).where(User.id == uid))
+            user = result.scalars().first()
+            if not user:
+                return {"status": "error", "message": "User not found."}
+
+            old_memory = user.memory_md
+
+            return await _save_memory(
+                updated_memory=updated_memory,
+                old_memory=old_memory,
+                llm=llm,
+                apply_fn=lambda content: setattr(user, "memory_md", content),
+                commit_fn=db_session.commit,
+                rollback_fn=db_session.rollback,
+                label="memory",
+                scope="user",
+            )
+        except Exception as e:
+            logger.exception("Failed to update user memory: %s", e)
+            await db_session.rollback()
+            return {
+                "status": "error",
+                "message": f"Failed to update memory: {e}",
+            }
+
+    return update_memory
+
+
+def create_update_team_memory_tool(
+    search_space_id: int,
+    db_session: AsyncSession,
+    llm: Any | None = None,
+):
+    @tool
+    async def update_memory(updated_memory: str) -> dict[str, Any]:
+        """Update the team's shared memory document for this search space.
+
+        Your current team memory is shown in <team_memory> in the system
+        prompt.  When the team shares important long-term information
+        (decisions, conventions, key facts, priorities), rewrite the memory
+        document to include the new information.  Merge new facts with
+        existing ones, update contradictions, remove outdated entries, and
+        keep it concise.
+
+        Args:
+            updated_memory: The FULL updated markdown document (not a diff).
+        """
+        try:
+            result = await db_session.execute(
+                select(SearchSpace).where(SearchSpace.id == search_space_id)
+            )
+            space = result.scalars().first()
+            if not space:
+                return {"status": "error", "message": "Search space not found."}
+
+            old_memory = space.shared_memory_md
+
+            return await _save_memory(
+                updated_memory=updated_memory,
+                old_memory=old_memory,
+                llm=llm,
+                apply_fn=lambda content: setattr(space, "shared_memory_md", content),
+                commit_fn=db_session.commit,
+                rollback_fn=db_session.rollback,
+                label="team memory",
+                scope="team",
+            )
+        except Exception as e:
+            logger.exception("Failed to update team memory: %s", e)
+            await db_session.rollback()
+            return {
+                "status": "error",
+                "message": f"Failed to update team memory: {e}",
+            }
+
+    return update_memory