diff --git a/alembic/versions/4537f0996495_add_start_end_for_agent_file.py b/alembic/versions/4537f0996495_add_start_end_for_agent_file.py
new file mode 100644
index 00000000..488bb0dd
--- /dev/null
+++ b/alembic/versions/4537f0996495_add_start_end_for_agent_file.py
@@ -0,0 +1,33 @@
+"""Add start end for agent file
+
+Revision ID: 4537f0996495
+Revises: 06fbbf65d4f1
+Create Date: 2025-07-25 17:44:26.748765
+
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "4537f0996495"
+down_revision: Union[str, None] = "06fbbf65d4f1"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column("files_agents", sa.Column("start_line", sa.Integer(), nullable=True))
+    op.add_column("files_agents", sa.Column("end_line", sa.Integer(), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column("files_agents", "end_line")
+    op.drop_column("files_agents", "start_line")
+    # ### end Alembic commands ###
diff --git a/letta/orm/file.py b/letta/orm/file.py
index 8cae2448..3229675f 100644
--- a/letta/orm/file.py
+++ b/letta/orm/file.py
@@ -103,6 +103,5 @@ class FileMetadata(SqlalchemyBase, OrganizationMixin, SourceMixin, AsyncAttrs):
             chunks_embedded=self.chunks_embedded,
             created_at=self.created_at,
             updated_at=self.updated_at,
-            is_deleted=self.is_deleted,
             content=content_text,
         )
diff --git a/letta/orm/files_agents.py b/letta/orm/files_agents.py
index 2a4cfde2..1c768711 100644
--- a/letta/orm/files_agents.py
+++ b/letta/orm/files_agents.py
@@ -2,14 +2,14 @@ import uuid
 from datetime import datetime
 from typing import TYPE_CHECKING, Optional
 
-from sqlalchemy import Boolean, DateTime, ForeignKey, Index, String, Text, UniqueConstraint, func
+from sqlalchemy import Boolean, DateTime, ForeignKey, Index, Integer, String, Text, UniqueConstraint, func
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
-from letta.constants import FILE_IS_TRUNCATED_WARNING
 from letta.orm.mixins import OrganizationMixin
 from letta.orm.sqlalchemy_base import SqlalchemyBase
 from letta.schemas.block import FileBlock as PydanticFileBlock
 from letta.schemas.file import FileAgent as PydanticFileAgent
+from letta.utils import truncate_file_visible_content
 
 if TYPE_CHECKING:
     pass
@@ -77,6 +77,12 @@ class FileAgent(SqlalchemyBase, OrganizationMixin):
         nullable=False,
         doc="UTC timestamp when this agent last accessed the file.",
     )
+    start_line: Mapped[Optional[int]] = mapped_column(
+        Integer, nullable=True, doc="Starting line number (1-indexed) when file was opened with line range."
+    )
+    end_line: Mapped[Optional[int]] = mapped_column(
+        Integer, nullable=True, doc="Ending line number (exclusive) when file was opened with line range."
+    )
 
     # relationships
     agent: Mapped["Agent"] = relationship(
@@ -87,13 +93,7 @@ class FileAgent(SqlalchemyBase, OrganizationMixin):
 
     # TODO: This is temporary as we figure out if we want FileBlock as a first class citizen
     def to_pydantic_block(self, per_file_view_window_char_limit: int) -> PydanticFileBlock:
-        visible_content = self.visible_content if self.visible_content and self.is_open else ""
-
-        # Truncate content and add warnings here when converting from FileAgent to Block
-        if len(visible_content) > per_file_view_window_char_limit:
-            truncated_warning = f"...[TRUNCATED]\n{FILE_IS_TRUNCATED_WARNING}"
-            visible_content = visible_content[: per_file_view_window_char_limit - len(truncated_warning)]
-            visible_content += truncated_warning
+        visible_content = truncate_file_visible_content(self.visible_content, self.is_open, per_file_view_window_char_limit)
 
         return PydanticFileBlock(
             value=visible_content,
diff --git a/letta/schemas/file.py b/letta/schemas/file.py
index 11a3356d..cfd67f87 100644
--- a/letta/schemas/file.py
+++ b/letta/schemas/file.py
@@ -56,7 +56,6 @@ class FileMetadata(FileMetadataBase):
     # orm metadata, optional fields
     created_at: Optional[datetime] = Field(default_factory=datetime.utcnow, description="The creation date of the file.")
     updated_at: Optional[datetime] = Field(default_factory=datetime.utcnow, description="The update date of the file.")
-    is_deleted: bool = Field(False, description="Whether this file is deleted or not.")
 
 
 class FileAgentBase(LettaBase):
@@ -76,8 +75,10 @@ class FileAgentBase(LettaBase):
     )
     last_accessed_at: Optional[datetime] = Field(
         default_factory=datetime.utcnow,
-        description="UTC timestamp of the agent’s most recent access to this file.",
+        description="UTC timestamp of the agent's most recent access to this file.",
     )
+    start_line: Optional[int] = Field(None, description="Starting line number (1-indexed) when file was opened with line range.")
+    end_line: Optional[int] = Field(None, description="Ending line number (exclusive) when file was opened with line range.")
 
 
 class FileAgent(FileAgentBase):
@@ -107,4 +108,3 @@ class FileAgent(FileAgentBase):
         default_factory=datetime.utcnow,
         description="Row last-update timestamp (UTC).",
     )
-    is_deleted: bool = Field(False, description="Soft-delete flag.")
diff --git a/letta/server/rest_api/routers/v1/agents.py b/letta/server/rest_api/routers/v1/agents.py
index d41d9cf1..2811dc95 100644
--- a/letta/server/rest_api/routers/v1/agents.py
+++ b/letta/server/rest_api/routers/v1/agents.py
@@ -41,7 +41,7 @@ from letta.server.server import SyncServer
 from letta.services.summarizer.enums import SummarizationMode
 from letta.services.telemetry_manager import NoopTelemetryManager
 from letta.settings import settings
-from letta.utils import safe_create_task
+from letta.utils import safe_create_task, truncate_file_visible_content
 
 # These can be forward refs, but because Fastapi needs them at runtime the must be imported normally
 
@@ -478,14 +478,23 @@ async def open_file(
     if not file_metadata:
         raise HTTPException(status_code=404, detail=f"File with id={file_id} not found")
 
+    # Process file content with line numbers using LineChunker
+    from letta.services.file_processor.chunker.line_chunker import LineChunker
+
+    content_lines = LineChunker().chunk_text(file_metadata=file_metadata, validate_range=False)
+    visible_content = "\n".join(content_lines)
+
+    # Truncate if needed
+    visible_content = truncate_file_visible_content(visible_content, True, per_file_view_window_char_limit)
+
     # Use enforce_max_open_files_and_open for efficient LRU handling
-    closed_files, was_already_open = await server.file_agent_manager.enforce_max_open_files_and_open(
+    closed_files, was_already_open, _ = await server.file_agent_manager.enforce_max_open_files_and_open(
         agent_id=agent_id,
         file_id=file_id,
         file_name=file_metadata.file_name,
         source_id=file_metadata.source_id,
         actor=actor,
-        visible_content=file_metadata.content[:per_file_view_window_char_limit] if file_metadata.content else "",
+        visible_content=visible_content,
         max_files_open=max_files_open,
     )
 
diff --git a/letta/services/file_processor/chunker/line_chunker.py b/letta/services/file_processor/chunker/line_chunker.py
index fe5ed031..c78399f1 100644
--- a/letta/services/file_processor/chunker/line_chunker.py
+++ b/letta/services/file_processor/chunker/line_chunker.py
@@ -130,37 +130,38 @@ class LineChunker:
         # Apply the appropriate chunking strategy
         if strategy == ChunkingStrategy.DOCUMENTATION:
             content_lines = self._chunk_by_sentences(text)
-        elif strategy == ChunkingStrategy.PROSE:
-            content_lines = self._chunk_by_characters(text)
         elif strategy == ChunkingStrategy.CODE:
             content_lines = self._chunk_by_lines(text, preserve_indentation=True)
         else:  # STRUCTURED_DATA or LINE_BASED
             content_lines = self._chunk_by_lines(text, preserve_indentation=False)
 
         total_chunks = len(content_lines)
-        chunk_type = (
-            "sentences" if strategy == ChunkingStrategy.DOCUMENTATION else "chunks" if strategy == ChunkingStrategy.PROSE else "lines"
-        )
+        chunk_type = "sentences" if strategy == ChunkingStrategy.DOCUMENTATION else "lines"
 
-        # Validate range if requested
-        if validate_range and (start is not None or end is not None):
-            if start is not None and start >= total_chunks:
-                # Convert to 1-indexed for user-friendly error message
-                start_display = start + 1
-                raise ValueError(
-                    f"File {file_metadata.file_name} has only {total_chunks} lines, but requested offset {start_display} is out of range"
-                )
-
-            if start is not None and end is not None and end > total_chunks:
-                # Convert to 1-indexed for user-friendly error message
-                start_display = start + 1
-                end_display = end
-                raise ValueError(
-                    f"File {file_metadata.file_name} has only {total_chunks} lines, but requested range {start_display} to {end_display} extends beyond file bounds"
-                )
-
-        # Handle start/end slicing
+        # Handle range validation and clamping
         if start is not None or end is not None:
+            # Always validate that start < end if both are specified
+            if start is not None and end is not None and start >= end:
+                if validate_range:
+                    raise ValueError(f"Invalid range: start ({start}) must be less than end ({end})")
+                # If validation is off, we still need to handle this case sensibly
+                # but we'll allow it to proceed with an empty result
+
+            # Always check that start is within bounds - this should error regardless of validation flag
+            if start is not None and start >= total_chunks:
+                raise ValueError(
+                    f"File {file_metadata.file_name} has only {total_chunks} {chunk_type}, but requested offset {start + 1} is out of range"
+                )
+
+            # Apply bounds checking
+            if start is not None:
+                start = max(0, start)  # Ensure non-negative
+
+            # Only clamp end if it exceeds the file length
+            if end is not None:
+                end = min(end, total_chunks)
+
+            # Apply slicing
             content_lines = content_lines[start:end]
             line_offset = start if start is not None else 0
         else:
diff --git a/letta/services/file_processor/file_processor.py b/letta/services/file_processor/file_processor.py
index d27597a4..76cac3d7 100644
--- a/letta/services/file_processor/file_processor.py
+++ b/letta/services/file_processor/file_processor.py
@@ -12,7 +12,6 @@ from letta.schemas.passage import Passage
 from letta.schemas.user import User
 from letta.services.agent_manager import AgentManager
 from letta.services.file_manager import FileManager
-from letta.services.file_processor.chunker.line_chunker import LineChunker
 from letta.services.file_processor.chunker.llama_index_chunker import LlamaIndexChunker
 from letta.services.file_processor.embedder.base_embedder import BaseEmbedder
 from letta.services.file_processor.parser.base_parser import FileParser
@@ -35,7 +34,6 @@ class FileProcessor:
         max_file_size: int = 50 * 1024 * 1024,  # 50MB default
     ):
         self.file_parser = file_parser
-        self.line_chunker = LineChunker()
         self.embedder = embedder
         self.max_file_size = max_file_size
         self.file_manager = FileManager()
diff --git a/letta/services/file_processor/file_types.py b/letta/services/file_processor/file_types.py
index b311a180..2816dd08 100644
--- a/letta/services/file_processor/file_types.py
+++ b/letta/services/file_processor/file_types.py
@@ -17,7 +17,6 @@ class ChunkingStrategy(str, Enum):
     CODE = "code"  # Line-based chunking for code files
     STRUCTURED_DATA = "structured_data"  # Line-based chunking for JSON, XML, etc.
     DOCUMENTATION = "documentation"  # Paragraph-aware chunking for Markdown, HTML
-    PROSE = "prose"  # Character-based wrapping for plain text
     LINE_BASED = "line_based"  # Default line-based chunking
 
 
@@ -44,7 +43,7 @@ class FileTypeRegistry:
         """Register all default supported file types."""
         # Document formats
         self.register(".pdf", "application/pdf", False, "PDF document", ChunkingStrategy.LINE_BASED)
-        self.register(".txt", "text/plain", True, "Plain text file", ChunkingStrategy.PROSE)
+        self.register(".txt", "text/plain", True, "Plain text file", ChunkingStrategy.LINE_BASED)
         self.register(".md", "text/markdown", True, "Markdown document", ChunkingStrategy.DOCUMENTATION)
         self.register(".markdown", "text/markdown", True, "Markdown document", ChunkingStrategy.DOCUMENTATION)
         self.register(".json", "application/json", True, "JSON data file", ChunkingStrategy.STRUCTURED_DATA)
diff --git a/letta/services/files_agents_manager.py b/letta/services/files_agents_manager.py
index e04ccb59..663edffe 100644
--- a/letta/services/files_agents_manager.py
+++ b/letta/services/files_agents_manager.py
@@ -1,5 +1,5 @@
 from datetime import datetime, timezone
-from typing import List, Optional, Union
+from typing import Dict, List, Optional, Union
 
 from sqlalchemy import and_, delete, func, or_, select, update
 
@@ -34,6 +34,8 @@ class FileAgentManager:
         max_files_open: int,
         is_open: bool = True,
         visible_content: Optional[str] = None,
+        start_line: Optional[int] = None,
+        end_line: Optional[int] = None,
     ) -> tuple[PydanticFileAgent, List[str]]:
         """
         Idempotently attach *file_id* to *agent_id* with LRU enforcement.
@@ -48,7 +50,7 @@ class FileAgentManager:
         """
         if is_open:
             # Use the efficient LRU + open method
-            closed_files, was_already_open = await self.enforce_max_open_files_and_open(
+            closed_files, was_already_open, _ = await self.enforce_max_open_files_and_open(
                 agent_id=agent_id,
                 file_id=file_id,
                 file_name=file_name,
@@ -56,6 +58,8 @@ class FileAgentManager:
                 actor=actor,
                 visible_content=visible_content or "",
                 max_files_open=max_files_open,
+                start_line=start_line,
+                end_line=end_line,
             )
 
             # Get the updated file agent to return
@@ -85,6 +89,8 @@ class FileAgentManager:
                         existing.visible_content = visible_content
 
                     existing.last_accessed_at = now_ts
+                    existing.start_line = start_line
+                    existing.end_line = end_line
 
                     await existing.update_async(session, actor=actor)
                     return existing.to_pydantic(), []
@@ -98,6 +104,8 @@ class FileAgentManager:
                     is_open=is_open,
                     visible_content=visible_content,
                     last_accessed_at=now_ts,
+                    start_line=start_line,
+                    end_line=end_line,
                 )
                 await assoc.create_async(session, actor=actor)
                 return assoc.to_pydantic(), []
@@ -112,6 +120,8 @@ class FileAgentManager:
         actor: PydanticUser,
         is_open: Optional[bool] = None,
         visible_content: Optional[str] = None,
+        start_line: Optional[int] = None,
+        end_line: Optional[int] = None,
     ) -> PydanticFileAgent:
         """Patch an existing association row."""
         async with db_registry.async_session() as session:
@@ -121,6 +131,10 @@ class FileAgentManager:
                 assoc.is_open = is_open
             if visible_content is not None:
                 assoc.visible_content = visible_content
+            if start_line is not None:
+                assoc.start_line = start_line
+            if end_line is not None:
+                assoc.end_line = end_line
 
             # touch timestamp
             assoc.last_accessed_at = datetime.now(timezone.utc)
@@ -373,8 +387,18 @@ class FileAgentManager:
     @enforce_types
     @trace_method
     async def enforce_max_open_files_and_open(
-        self, *, agent_id: str, file_id: str, file_name: str, source_id: str, actor: PydanticUser, visible_content: str, max_files_open: int
-    ) -> tuple[List[str], bool]:
+        self,
+        *,
+        agent_id: str,
+        file_id: str,
+        file_name: str,
+        source_id: str,
+        actor: PydanticUser,
+        visible_content: str,
+        max_files_open: int,
+        start_line: Optional[int] = None,
+        end_line: Optional[int] = None,
+    ) -> tuple[List[str], bool, Dict[str, tuple[Optional[int], Optional[int]]]]:
         """
         Efficiently handle LRU eviction and file opening in a single transaction.
 
@@ -387,7 +411,8 @@ class FileAgentManager:
             visible_content: Content to set for the opened file
 
         Returns:
-            Tuple of (closed_file_names, file_was_already_open)
+            Tuple of (closed_file_names, file_was_already_open, previous_ranges)
+            where previous_ranges maps file names to their old (start_line, end_line) ranges
         """
         async with db_registry.async_session() as session:
             # Single query to get ALL open files for this agent, ordered by last_accessed_at (oldest first)
@@ -423,6 +448,17 @@ class FileAgentManager:
 
             file_was_already_open = file_to_open is not None and file_to_open.is_open
 
+            # Capture previous line range if file was already open and we're changing the range
+            previous_ranges = {}
+            if file_was_already_open and file_to_open:
+                old_start = file_to_open.start_line
+                old_end = file_to_open.end_line
+                # Only record if there was a previous range or if we're setting a new range
+                if old_start is not None or old_end is not None or start_line is not None or end_line is not None:
+                    # Only record if the range is actually changing
+                    if old_start != start_line or old_end != end_line:
+                        previous_ranges[file_name] = (old_start, old_end)
+
             # Calculate how many files need to be closed
             current_other_count = len(other_open_files)
             target_other_count = max_files_open - 1  # Reserve 1 slot for file we're opening
@@ -458,6 +494,8 @@ class FileAgentManager:
                 file_to_open.is_open = True
                 file_to_open.visible_content = visible_content
                 file_to_open.last_accessed_at = now_ts
+                file_to_open.start_line = start_line
+                file_to_open.end_line = end_line
                 await file_to_open.update_async(session, actor=actor)
             else:
                 # Create new file association
@@ -470,10 +508,12 @@ class FileAgentManager:
                     is_open=True,
                     visible_content=visible_content,
                     last_accessed_at=now_ts,
+                    start_line=start_line,
+                    end_line=end_line,
                 )
                 await new_file_agent.create_async(session, actor=actor)
 
-            return closed_file_names, file_was_already_open
+            return closed_file_names, file_was_already_open, previous_ranges
 
     @enforce_types
     @trace_method
diff --git a/letta/services/tool_executor/files_tool_executor.py b/letta/services/tool_executor/files_tool_executor.py
index 6e5a6304..8e207942 100644
--- a/letta/services/tool_executor/files_tool_executor.py
+++ b/letta/services/tool_executor/files_tool_executor.py
@@ -142,6 +142,7 @@ class LettaFileToolExecutor(ToolExecutor):
         # Process each file
         opened_files = []
         all_closed_files = []
+        all_previous_ranges = {}  # Collect all previous ranges from all files
 
         for file_request in file_requests:
             file_name = file_request.file_name
@@ -181,7 +182,7 @@ class LettaFileToolExecutor(ToolExecutor):
             visible_content = "\n".join(content_lines)
 
             # Handle LRU eviction and file opening
-            closed_files, was_already_open = await self.files_agents_manager.enforce_max_open_files_and_open(
+            closed_files, was_already_open, previous_ranges = await self.files_agents_manager.enforce_max_open_files_and_open(
                 agent_id=agent_state.id,
                 file_id=file_id,
                 file_name=file_name,
@@ -189,42 +190,45 @@ class LettaFileToolExecutor(ToolExecutor):
                 actor=self.actor,
                 visible_content=visible_content,
                 max_files_open=agent_state.max_files_open,
+                start_line=start + 1 if start is not None else None,  # convert to 1-indexed for user display
+                end_line=end if end is not None else None,  # end is already exclusive in slicing, so this is correct
             )
 
             opened_files.append(file_name)
             all_closed_files.extend(closed_files)
+            all_previous_ranges.update(previous_ranges)  # Merge previous ranges from this file
 
         # Update access timestamps for all opened files efficiently
         await self.files_agents_manager.mark_access_bulk(agent_id=agent_state.id, file_names=file_names, actor=self.actor)
 
-        # Build success message
-        if len(file_requests) == 1:
-            # Single file - maintain existing format
-            file_request = file_requests[0]
-            file_name = file_request.file_name
-            offset = file_request.offset
-            length = file_request.length
-            if offset is not None and length is not None:
-                end_line = offset + length - 1
-                success_msg = (
-                    f"Successfully opened file {file_name}, lines {offset} to {end_line} are now visible in memory block <{file_name}>"
-                )
-            elif offset is not None:
-                success_msg = f"Successfully opened file {file_name}, lines {offset} to end are now visible in memory block <{file_name}>"
-            else:
-                success_msg = f"Successfully opened file {file_name}, entire file is now visible in memory block <{file_name}>"
-        else:
-            # Multiple files - show individual ranges if specified
-            file_summaries = []
-            for req in file_requests:
-                if req.offset is not None and req.length is not None:
-                    end_line = req.offset + req.length - 1
-                    file_summaries.append(f"{req.file_name} (lines {req.offset}-{end_line})")
-                elif req.offset is not None:
-                    file_summaries.append(f"{req.file_name} (lines {req.offset}-end)")
+        # Helper function to format previous range info
+        def format_previous_range(file_name: str) -> str:
+            if file_name in all_previous_ranges:
+                old_start, old_end = all_previous_ranges[file_name]
+                if old_start is not None and old_end is not None:
+                    return f" (previously lines {old_start}-{old_end})"
+                elif old_start is not None:
+                    return f" (previously lines {old_start}-end)"
                 else:
-                    file_summaries.append(req.file_name)
-            success_msg = f"Successfully opened {len(file_requests)} files: {', '.join(file_summaries)}"
+                    return " (previously full file)"
+            return ""
+
+        # Build unified success message - treat single and multiple files consistently
+        file_summaries = []
+        for req in file_requests:
+            previous_info = format_previous_range(req.file_name)
+            if req.offset is not None and req.length is not None:
+                end_line = req.offset + req.length - 1
+                file_summaries.append(f"{req.file_name} (lines {req.offset}-{end_line}){previous_info}")
+            elif req.offset is not None:
+                file_summaries.append(f"{req.file_name} (lines {req.offset}-end){previous_info}")
+            else:
+                file_summaries.append(f"{req.file_name}{previous_info}")
+
+        if len(file_requests) == 1:
+            success_msg = f"* Opened {file_summaries[0]}"
+        else:
+            success_msg = f"* Opened {len(file_requests)} files: {', '.join(file_summaries)}"
 
         # Add information about closed files
         if closed_by_close_all_others:
diff --git a/letta/utils.py b/letta/utils.py
index 73abb1a3..2d2775ff 100644
--- a/letta/utils.py
+++ b/letta/utils.py
@@ -32,6 +32,7 @@ from letta.constants import (
     DEFAULT_CORE_MEMORY_SOURCE_CHAR_LIMIT,
     DEFAULT_MAX_FILES_OPEN,
     ERROR_MESSAGE_PREFIX,
+    FILE_IS_TRUNCATED_WARNING,
     LETTA_DIR,
     MAX_FILENAME_LENGTH,
     TOOL_CALL_ID_MAX_LEN,
@@ -1223,3 +1224,15 @@ def calculate_file_defaults_based_on_context_window(context_window: Optional[int
         return 10, 40_000  # ~100k tokens
     else:  # Extremely large models (200K+)
         return 15, 40_000  # ~1505k tokens
+
+
+def truncate_file_visible_content(visible_content: str, is_open: bool, per_file_view_window_char_limit: int):
+    visible_content = visible_content if visible_content and is_open else ""
+
+    # Truncate content and add warnings here when converting from FileAgent to Block
+    if len(visible_content) > per_file_view_window_char_limit:
+        truncated_warning = f"...[TRUNCATED]\n{FILE_IS_TRUNCATED_WARNING}"
+        visible_content = visible_content[: per_file_view_window_char_limit - len(truncated_warning)]
+        visible_content += truncated_warning
+
+    return visible_content
diff --git a/tests/test_managers.py b/tests/test_managers.py
index 5e6da65c..28b5cdcb 100644
--- a/tests/test_managers.py
+++ b/tests/test_managers.py
@@ -8733,6 +8733,71 @@ async def test_update_file_agent_by_file_name(server, file_attachment, default_u
     )
     assert updated.is_open is False
     assert updated.visible_content == "updated"
+    assert updated.start_line is None  # start_line should default to None
+    assert updated.end_line is None  # end_line should default to None
+
+
+@pytest.mark.asyncio
+async def test_file_agent_line_tracking(server, default_user, sarah_agent, default_source):
+    """Test that line information is captured when opening files with line ranges"""
+    from letta.schemas.file import FileMetadata as PydanticFileMetadata
+
+    # Create a test file with multiple lines
+    test_content = "line 1\nline 2\nline 3\nline 4\nline 5"
+    file_metadata = PydanticFileMetadata(
+        file_name="test_lines.txt",
+        organization_id=default_user.organization_id,
+        source_id=default_source.id,
+    )
+    file = await server.file_manager.create_file(file_metadata=file_metadata, actor=default_user, text=test_content)
+
+    # Test opening with line range using enforce_max_open_files_and_open
+    closed_files, was_already_open, previous_ranges = await server.file_agent_manager.enforce_max_open_files_and_open(
+        agent_id=sarah_agent.id,
+        file_id=file.id,
+        file_name=file.file_name,
+        source_id=file.source_id,
+        actor=default_user,
+        visible_content="2: line 2\n3: line 3",
+        max_files_open=sarah_agent.max_files_open,
+        start_line=2,  # 1-indexed
+        end_line=4,  # exclusive
+    )
+
+    # Retrieve and verify line tracking
+    retrieved = await server.file_agent_manager.get_file_agent_by_id(
+        agent_id=sarah_agent.id,
+        file_id=file.id,
+        actor=default_user,
+    )
+
+    assert retrieved.start_line == 2
+    assert retrieved.end_line == 4
+    assert previous_ranges == {}  # No previous range since it wasn't open before
+
+    # Test opening without line range - should clear line info and capture previous range
+    closed_files, was_already_open, previous_ranges = await server.file_agent_manager.enforce_max_open_files_and_open(
+        agent_id=sarah_agent.id,
+        file_id=file.id,
+        file_name=file.file_name,
+        source_id=file.source_id,
+        actor=default_user,
+        visible_content="full file content",
+        max_files_open=sarah_agent.max_files_open,
+        start_line=None,
+        end_line=None,
+    )
+
+    # Retrieve and verify line info is cleared
+    retrieved = await server.file_agent_manager.get_file_agent_by_id(
+        agent_id=sarah_agent.id,
+        file_id=file.id,
+        actor=default_user,
+    )
+
+    assert retrieved.start_line is None
+    assert retrieved.end_line is None
+    assert previous_ranges == {file.file_name: (2, 4)}  # Should capture the previous range
 
 
 @pytest.mark.asyncio
@@ -9131,7 +9196,7 @@ async def test_lru_eviction_on_open_file(server, default_user, sarah_agent, defa
     time.sleep(0.1)
 
     # Now "open" the last file using the efficient method
-    closed_files, was_already_open = await server.file_agent_manager.enforce_max_open_files_and_open(
+    closed_files, was_already_open, _ = await server.file_agent_manager.enforce_max_open_files_and_open(
         agent_id=sarah_agent.id,
         file_id=files[-1].id,
         file_name=files[-1].file_name,
@@ -9205,7 +9270,7 @@ async def test_lru_no_eviction_when_reopening_same_file(server, default_user, sa
     time.sleep(0.1)
 
     # "Reopen" the last file (which is already open)
-    closed_files, was_already_open = await server.file_agent_manager.enforce_max_open_files_and_open(
+    closed_files, was_already_open, _ = await server.file_agent_manager.enforce_max_open_files_and_open(
         agent_id=sarah_agent.id,
         file_id=files[-1].id,
         file_name=files[-1].file_name,
diff --git a/tests/test_sources.py b/tests/test_sources.py
index e9315c3b..6343957a 100644
--- a/tests/test_sources.py
+++ b/tests/test_sources.py
@@ -287,11 +287,11 @@ def test_attach_existing_files_creates_source_blocks_correctly(disable_pinecone,
 <file status="open" name="test_source/test.txt">
 <metadata>
 - read_only=true
-- chars_current=46
+- chars_current=45
 - chars_limit=15000
 </metadata>
 <value>
-[Viewing file start (out of 1 chunks)]
+[Viewing file start (out of 1 lines)]
 1: test
 </value>
 </file>
@@ -348,11 +348,11 @@ def test_delete_source_removes_source_blocks_correctly(disable_pinecone, client:
 <file status="open" name="test_source/test.txt">
 <metadata>
 - read_only=true
-- chars_current=46
+- chars_current=45
 - chars_limit=15000
 </metadata>
 <value>
-[Viewing file start (out of 1 chunks)]
+[Viewing file start (out of 1 lines)]
 1: test
 </value>
 </file>
@@ -437,9 +437,9 @@ def test_agent_uses_open_close_file_correctly(disable_pinecone, client: LettaSDK
     assert old_content_length > 10, f"Expected content > 10 chars for offset={offset}, length={length}, got {old_content_length}"
 
     # Assert specific content expectations for first range (lines 1-5)
-    assert "[Viewing chunks 1 to 5 (out of 554 chunks)]" in old_value, f"Expected viewing header for lines 1-5, got: {old_value[:100]}..."
+    assert "[Viewing lines 1 to 5 (out of " in old_value, f"Expected viewing header for lines 1-5, got: {old_value[:100]}..."
     assert "1: Enrico Letta" in old_value, f"Expected line 1 to start with '1: Enrico Letta', got: {old_value[:200]}..."
-    assert "5: appointed to the Cabinet" in old_value, f"Expected line 5 to contain '5: appointed to the Cabinet', got: {old_value}"
+    assert "5: " in old_value, f"Expected line 5 to be present, got: {old_value}"
 
     # Ask agent to open the file for a different range
     offset, length = 6, 5  # Different offset, same length
@@ -466,13 +466,9 @@ def test_agent_uses_open_close_file_correctly(disable_pinecone, client: LettaSDK
     assert new_content_length > 10, f"Expected content > 10 chars for offset={offset}, length={length}, got {new_content_length}"
 
     # Assert specific content expectations for second range (lines 6-10)
-    assert "[Viewing chunks 6 to 10 (out of 554 chunks)]" in new_value, f"Expected viewing header for lines 6-10, got: {new_value[:100]}..."
-    assert (
-        "6: was promoted to become Minister" in new_value
-    ), f"Expected line 6 to start with '6: was promoted to become Minister', got: {new_value[:200]}..."
-    assert (
-        "10: produced an inconclusive result" in new_value
-    ), f"Expected line 10 to contain '10: produced an inconclusive result', got: {new_value}"
+    assert "[Viewing lines 6 to 10 (out of " in new_value, f"Expected viewing header for lines 6-10, got: {new_value[:100]}..."
+    assert "6: " in new_value, f"Expected line 6 to be present, got: {new_value[:200]}..."
+    assert "10: " in new_value, f"Expected line 10 to be present, got: {new_value}"
 
     print(f"Comparing content ranges:")
     print(f"  First range (offset=1, length=5):  '{old_value}'")
@@ -663,7 +659,7 @@ def test_create_agent_with_source_ids_creates_source_blocks_correctly(disable_pi
     # Check that source blocks were created correctly
     blocks = temp_agent_state.memory.file_blocks
     assert len(blocks) == 1
-    assert any(b.value.startswith("[Viewing file start (out of 554 chunks)]") for b in blocks)
+    assert any(b.value.startswith("[Viewing file start (out of ") for b in blocks)
 
     # Verify file tools were automatically attached
     file_tools = {tool.name for tool in temp_agent_state.tools if tool.tool_type == ToolType.LETTA_FILES_CORE}
@@ -1000,6 +996,10 @@ def test_agent_open_file(disable_pinecone, client: LettaSDKClient, agent_state:
     closed_files = client.agents.files.open(agent_id=agent_state.id, file_id=file_metadata.id)
     assert len(closed_files) == 0
 
+    system = get_raw_system_message(client, agent_state.id)
+    assert '<file status="open" name="test_source/test.txt">' in system
+    assert "[Viewing file start (out of 1 lines)]" in system
+
 
 def test_agent_close_file(disable_pinecone, client: LettaSDKClient, agent_state: AgentState):
     """Test client.agents.close_file() function"""
@@ -1019,9 +1019,8 @@ def test_agent_close_file(disable_pinecone, client: LettaSDKClient, agent_state:
     # Test close_file function
     client.agents.files.close(agent_id=agent_state.id, file_id=file_metadata.id)
 
-    # Result can be None or any type based on the signature
-    # Just verify the function executes without error
-    assert True, "close_file should execute without error"
+    system = get_raw_system_message(client, agent_state.id)
+    assert '<file status="closed" name="test_source/test.txt">' in system
 
 
 def test_agent_close_all_open_files(disable_pinecone, client: LettaSDKClient, agent_state: AgentState):
@@ -1041,6 +1040,9 @@ def test_agent_close_all_open_files(disable_pinecone, client: LettaSDKClient, ag
         # Open each file
         client.agents.files.open(agent_id=agent_state.id, file_id=file_metadata.id)
 
+    system = get_raw_system_message(client, agent_state.id)
+    assert '<file status="open"' in system
+
     # Test close_all_open_files function
     result = client.agents.files.close_all(agent_id=agent_state.id)
 
@@ -1048,6 +1050,9 @@ def test_agent_close_all_open_files(disable_pinecone, client: LettaSDKClient, ag
     assert isinstance(result, list), f"Expected list, got {type(result)}"
     assert all(isinstance(item, str) for item in result), "All items in result should be strings"
 
+    system = get_raw_system_message(client, agent_state.id)
+    assert '<file status="open"' not in system
+
 
 def test_file_processing_timeout(disable_pinecone, client: LettaSDKClient):
     """Test that files in non-terminal states are moved to error after timeout"""
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 87cfc127..30c3a121 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -445,19 +445,24 @@ def test_line_chunker_out_of_range_start():
     file = FileMetadata(file_name="test.py", source_id="test_source", content="line1\nline2\nline3")
     chunker = LineChunker()
 
-    # Test with start beyond file length (3 lines, requesting start=5 which is 0-indexed 4)
+    # Test with start beyond file length - should raise ValueError
     with pytest.raises(ValueError, match="File test.py has only 3 lines, but requested offset 6 is out of range"):
         chunker.chunk_text(file, start=5, end=6, validate_range=True)
 
 
 def test_line_chunker_out_of_range_end():
-    """Test that LineChunker throws error when end extends beyond file bounds"""
+    """Test that LineChunker clamps end when it extends beyond file bounds"""
     file = FileMetadata(file_name="test.py", source_id="test_source", content="line1\nline2\nline3")
     chunker = LineChunker()
 
     # Test with end beyond file length (3 lines, requesting 1 to 10)
-    with pytest.raises(ValueError, match="File test.py has only 3 lines, but requested range 1 to 10 extends beyond file bounds"):
-        chunker.chunk_text(file, start=0, end=10, validate_range=True)
+    # Should clamp end to file length and return lines 1-3
+    result = chunker.chunk_text(file, start=0, end=10, validate_range=True)
+    assert len(result) == 4  # metadata header + 3 lines
+    assert "[Viewing lines 1 to 3 (out of 3 lines)]" in result[0]
+    assert "1: line1" in result[1]
+    assert "2: line2" in result[2]
+    assert "3: line3" in result[3]
 
 
 def test_line_chunker_edge_case_empty_file():
@@ -478,21 +483,24 @@ def test_line_chunker_edge_case_single_line():
     result = chunker.chunk_text(file, start=0, end=1, validate_range=True)
     assert "1: only line" in result[1]
 
-    # Test out of range for single line file
+    # Test out of range for single line file - should raise error
     with pytest.raises(ValueError, match="File single.py has only 1 lines, but requested offset 2 is out of range"):
         chunker.chunk_text(file, start=1, end=2, validate_range=True)
 
 
 def test_line_chunker_validation_disabled_allows_out_of_range():
-    """Test that when validation is disabled, out of range silently returns partial results"""
+    """Test that out-of-bounds start always raises error, but invalid ranges (start>=end) are allowed when validation is off"""
     file = FileMetadata(file_name="test.py", source_id="test_source", content="line1\nline2\nline3")
     chunker = LineChunker()
 
-    # Test with validation disabled - should not raise error
-    result = chunker.chunk_text(file, start=5, end=10, validate_range=False)
-    # Should return empty content (except metadata header) since slice is out of bounds
+    # Test 1: Out of bounds start should always raise error, even with validation disabled
+    with pytest.raises(ValueError, match="File test.py has only 3 lines, but requested offset 6 is out of range"):
+        chunker.chunk_text(file, start=5, end=10, validate_range=False)
+
+    # Test 2: With validation disabled, start >= end should be allowed (but gives empty result)
+    result = chunker.chunk_text(file, start=2, end=2, validate_range=False)
     assert len(result) == 1  # Only metadata header
-    assert "[Viewing lines 6 to 10 (out of 3 lines)]" in result[0]
+    assert "[Viewing lines 3 to 2 (out of 3 lines)]" in result[0]
 
 
 def test_line_chunker_only_start_parameter():
@@ -506,7 +514,7 @@ def test_line_chunker_only_start_parameter():
     assert "2: line2" in result[1]
     assert "3: line3" in result[2]
 
-    # Test invalid start only
+    # Test start at end of file - should raise error
     with pytest.raises(ValueError, match="File test.py has only 3 lines, but requested offset 4 is out of range"):
         chunker.chunk_text(file, start=3, validate_range=True)