envsitter-guard

OpenCode plugin that prevents agents/tools from reading or editing sensitive .env* files, while still allowing safe inspection via EnvSitter (keys + deterministic fingerprints; never values).

Quickstart (OpenCode)

OpenCode supports loading plugins from npm or local plugin files.

Reference docs:

• https://opencode.ai/docs/plugins/
• https://opencode.ai/docs/config/#plugins

Option A (recommended): load from npm via opencode.json

Add the plugin package to your OpenCode config.

opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["envsitter-guard@latest"]
}

Restart OpenCode after updating config.

Why

Accidentally printing .env contents is one of the easiest ways for an agentic workflow to leak secrets into:

• chat transcripts
• logs/tool output
• commits/patches
• screenshots / shared sessions

envsitter-guard blocks risky operations and points you to safe alternatives.

This plugin is built on top of envsitter, a library for safely inspecting and matching .env secrets without ever printing values.

What it does

This plugin provides safe EnvSitter-backed tools and blocks sensitive file access via OpenCode tool hooks.

Safe tools (no values)

These tools never return raw .env values:

Reading:

• envsitter_keys: list keys in a dotenv file
• envsitter_fingerprint: deterministic fingerprint of a single key's value
• envsitter_scan: scan value shapes (jwt/url/base64) without printing values

Matching:

• envsitter_match: boolean/shape checks and outside-in candidate matching (without printing values)
• envsitter_match_by_key: bulk candidate-by-key matching (returns booleans only)

Mutations:

• envsitter_add: add a new key (fails if key exists)
• envsitter_set: set a key's value (creates or updates)
• envsitter_unset: unset a key's value (sets to empty, keeps the key)
• envsitter_delete: delete key(s) entirely from the file

File Operations:

• envsitter_validate: validate dotenv syntax (no values; issues only)
• envsitter_copy: copy keys between env files (no values; plan + line numbers only)
• envsitter_format / envsitter_reorder: reorder/format env files (no values)
• envsitter_annotate: add comments near keys (no values)

Help:

• envsitter_help: comprehensive usage guide for all tools (topics: overview, reading, matching, mutations, file_ops, all)

Notes for file operations:

• File operations are dry-run unless write: true is provided.
• Tools only return keys, booleans, and line numbers/operation plans.

Blocking behavior

• Sensitive paths: .env, .env.local, .env.production, etc. (.env*)
• Allowed: .env.example
• Always blocked: .envsitter/pepper

Blocked operations via tool hooks:

• read on sensitive .env* paths
• edit / write / patch / multiedit on sensitive .env* paths

When blocked, the plugin throws an error with guidance on which EnvSitter tools to use instead.

Tools

Tools only operate on .env-style files inside the current project.

• Most tools accept a filePath that defaults to .env.
• File operations are dry-run unless write: true is provided.

envsitter_keys

Lists keys in a dotenv file.

• Input: { "filePath"?: string, "filterRegex"?: string }
• Output: JSON { file, keys }

Example (inside OpenCode):

{ "tool": "envsitter_keys", "args": { "filePath": ".env" } }

Optional filtering:

{ "tool": "envsitter_keys", "args": { "filePath": ".env", "filterRegex": "/^(API_|DB_)/" } }

envsitter_fingerprint

Computes a deterministic fingerprint of a single key.

• Input: { "filePath"?: string, "key": string }
• Output: JSON { file, key, result }

Example (inside OpenCode):

{ "tool": "envsitter_fingerprint", "args": { "filePath": ".env", "key": "DATABASE_URL" } }

envsitter_match

Matches key values without printing them.

• Input:
  • { "filePath"?: string, "op"?: string, "key"?: string, "keys"?: string[], "allKeys"?: boolean, "candidate"?: string, "candidateEnvVar"?: string }
• Output:
  • If key provided: JSON { file, key, op, match }
  • If keys or allKeys: JSON { file, op, matches }

Notes:

• Provide exactly one selector: key, keys, or allKeys: true.
• For ops that compare against a candidate (is_equal, partial_match_*), provide candidate or candidateEnvVar.

Examples (inside OpenCode):

{ "tool": "envsitter_match", "args": { "filePath": ".env", "key": "SENTRY_DSN", "op": "exists" } }

{ "tool": "envsitter_match", "args": { "filePath": ".env", "key": "PORT", "op": "is_number" } }

{ "tool": "envsitter_match", "args": { "filePath": ".env", "key": "NODE_ENV", "op": "is_equal", "candidate": "production" } }

envsitter_match_by_key

Bulk match candidates-by-key without printing values (returns booleans only).

• Input:
  • { "filePath"?: string, "candidatesByKey"?: Record<string,string>, "candidatesByKeyJson"?: string, "candidatesByKeyEnvVar"?: string }
• Output: JSON { file, matches }

Note: provide exactly one of candidatesByKey, candidatesByKeyJson, or candidatesByKeyEnvVar.

Example (inside OpenCode):

{ "tool": "envsitter_match_by_key", "args": { "filePath": ".env", "candidatesByKey": { "NODE_ENV": "production" } } }

envsitter_scan

Scan value shapes (jwt/url/base64) without printing values.

• Input: { "filePath"?: string, "detect"?: ("jwt"|"url"|"base64")[], "keysFilterRegex"?: string }
• Output: JSON { file, findings }

Example (inside OpenCode):

{ "tool": "envsitter_scan", "args": { "filePath": ".env", "detect": ["jwt", "url"] } }

envsitter_validate

Validate dotenv syntax.

• Input: { "filePath"?: string }
• Output: JSON { file, ok, issues }

Example (inside OpenCode):

{ "tool": "envsitter_validate", "args": { "filePath": ".env" } }

envsitter_copy

Copy keys between env files. Output includes a plan (keys + line numbers), never values.

• Input:
  • { "from": string, "to": string, "keys"?: string[], "includeRegex"?: string, "excludeRegex"?: string, "rename"?: string, "onConflict"?: "error"|"skip"|"overwrite", "write"?: boolean }
• Output: JSON { from, to, onConflict, willWrite, wrote, hasChanges, issues, plan }

Examples (inside OpenCode):

{ "tool": "envsitter_copy", "args": { "from": ".env.production", "to": ".env.staging", "keys": ["API_URL"], "onConflict": "overwrite" } }

{ "tool": "envsitter_copy", "args": { "from": ".env.production", "to": ".env.staging", "keys": ["API_URL"], "onConflict": "overwrite", "write": true } }

envsitter_format / envsitter_reorder

Format/reorder an env file (no values in output).

• Input: { "filePath"?: string, "mode"?: "sections"|"global", "sort"?: "alpha"|"none", "write"?: boolean }
• Output: JSON { file, mode, sort, willWrite, wrote, hasChanges, issues }

Example (inside OpenCode):

{ "tool": "envsitter_format", "args": { "filePath": ".env", "mode": "sections", "sort": "alpha", "write": true } }

envsitter_annotate

Annotate an env key with a comment (no values in output).

• Input: { "filePath"?: string, "key": string, "comment": string, "line"?: number, "write"?: boolean }
• Output: JSON { file, key, willWrite, wrote, hasChanges, issues, plan }

Example (inside OpenCode):

{ "tool": "envsitter_annotate", "args": { "filePath": ".env", "key": "DATABASE_URL", "comment": "prod only", "write": true } }

envsitter_add

Add a new key to a dotenv file (fails if key already exists).

• Input: { "filePath"?: string, "key": string, "value": string, "write"?: boolean }
• Output: JSON { file, key, willWrite, wrote, hasChanges, issues, plan }

Example (inside OpenCode):

{ "tool": "envsitter_add", "args": { "filePath": ".env", "key": "NEW_API_KEY", "value": "sk-xxx", "write": true } }

envsitter_set

Set a key's value in a dotenv file (creates if missing, updates if exists).

• Input: { "filePath"?: string, "key": string, "value": string, "write"?: boolean }
• Output: JSON { file, key, willWrite, wrote, hasChanges, issues, plan }

Example (inside OpenCode):

{ "tool": "envsitter_set", "args": { "filePath": ".env", "key": "API_KEY", "value": "new-value", "write": true } }

envsitter_unset

Unset a key's value (sets to empty string, keeps the key line).

• Input: { "filePath"?: string, "key": string, "write"?: boolean }
• Output: JSON { file, key, willWrite, wrote, hasChanges, issues, plan }

Example (inside OpenCode):

{ "tool": "envsitter_unset", "args": { "filePath": ".env", "key": "OLD_KEY", "write": true } }

envsitter_delete

Delete key(s) from a dotenv file entirely (removes the line).

• Input: { "filePath"?: string, "keys": string[], "write"?: boolean }
• Output: JSON { file, keys, willWrite, wrote, hasChanges, issues, plan }

Example (inside OpenCode):

{ "tool": "envsitter_delete", "args": { "filePath": ".env", "keys": ["OLD_KEY", "UNUSED_KEY"], "write": true } }

envsitter_help

Get comprehensive help on all EnvSitter tools.

• Input: { "topic"?: "overview" | "reading" | "matching" | "mutations" | "file_ops" | "all" }
• Output: Markdown documentation for the requested topic

Topics:

• overview: What EnvSitter is and tool categories
• reading: envsitter_keys, envsitter_fingerprint, envsitter_scan
• matching: envsitter_match, envsitter_match_by_key with all operators
• mutations: envsitter_add, envsitter_set, envsitter_unset, envsitter_delete
• file_ops: envsitter_validate, envsitter_copy, envsitter_format, envsitter_annotate
• all: Full guide (default)

Example (inside OpenCode):

{ "tool": "envsitter_help", "args": { "topic": "mutations" } }

Install & enable in OpenCode (alternatives)

Option B: local plugin file (project-level)

If you want a local plugin file in-repo (or need local overrides), create .opencode/plugin/envsitter-guard.ts:

import EnvSitterGuard from "envsitter-guard";

export default EnvSitterGuard;
export { EnvSitterGuard } from "envsitter-guard";

Then create .opencode/package.json with the dependency so OpenCode can install it:

{
  "dependencies": {
    "envsitter-guard": "latest"
  }
}

Restart OpenCode; files in .opencode/plugin/ are loaded automatically.

Option C: global plugin file

Place a plugin file in ~/.config/opencode/plugin/ if you want it enabled for all projects.

(You can use the same contents as Option B.)

Development

Install

npm ci

Typecheck

npm run typecheck

Test

npm test

Build (for publishing)

npm run build

Related

• envsitter — The underlying library this plugin is built on. Provides CLI and programmatic API for safe .env inspection.
• EnvSitter CLI: npx envsitter keys --file .env (alternative to plugin tools)

Notes

• This project intentionally avoids reading or printing .env values.
• All tools return keys, booleans, line numbers, and operation plans — never secret values.

License

MIT. See LICENSE.