Apply one unified diff hunk to the current buffer or an optional file path. useLatestChangedTick is current-buffer-only; useLatestSessionChangedTick works for explicit path targets or already-open explicit bufferId targets in the editor session.
AI agents use apply_hunk to create or update resources in Vigentic MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Vigentic MCP environment.
apply_hunk applies a diff patch to a file or buffer, which is a reversible modification of data (Write category). It does not permanently delete data (Destructive), execute arbitrary code (Execute), nor move money (Financial).
From the tool's definition Tool description states it 'Apply[s] one unified diff hunk' to a buffer or file, which modifies file content. The sibling tools like apply_edit_batch, create_file, delete_file, and apply_multi_file_batch confirm this server manages file and buffer mutations.
Attacks that exploit this kind of access
Apply one unified diff hunk to the current buffer or an optional file path. useLatestChangedTick is current-buffer-only; useLatestSessionChangedTick works for explicit path targets or already-open explicit bufferId targets in the editor session. It is categorised as a Write tool in the Vigentic MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Vigentic MCP server in PolicyLayer and add a rule for apply_hunk: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Vigentic MCP. Nothing to install.
apply_hunk is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the apply_hunk rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for apply_hunk. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
apply_hunk is provided by the Vigentic MCP server (munozu/vigentic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
apply_hunk is one line of Vigentic's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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