Inferensys

Prompt

CLI Plugin and Extension Reference Prompt

A practical prompt playbook for generating a complete plugin developer reference from source code, interface definitions, and plugin manifests.
Developer doing prompt engineering on laptop, prompt variations visible on screen, casual coding session.
PROMPT PLAYBOOK

When to Use This Prompt

Defines the ideal conditions, required inputs, and clear anti-patterns for using the CLI Plugin and Extension Reference Prompt.

This prompt is designed for CLI platform engineers who own a plugin system and need to produce a complete, accurate developer reference from working code. The ideal user has direct access to the plugin loading source code, the interface or abstract base class that plugins must implement, and at least one reference plugin implementation that demonstrates the contract correctly. The job-to-be-done is turning these implementation artifacts into a structured document that plugin developers can rely on: installation paths, API contracts, lifecycle hooks, version compatibility constraints, and discovery mechanisms. If you are maintaining a CLI tool that supports extensions and you need to onboard third-party developers, this prompt converts your internal implementation knowledge into an external-facing reference.

You should use this prompt when you can provide concrete source artifacts. The prompt expects placeholders like [PLUGIN_LOADER_SOURCE] for the code that discovers and initializes plugins, [PLUGIN_INTERFACE_DEFINITION] for the abstract class or interface that plugins must satisfy, and [REFERENCE_PLUGIN_SOURCE] for a working example that validates the contract. The harness around this prompt should validate the generated reference against the actual plugin loading code to catch mismatches in method signatures, expected return types, or lifecycle hook ordering. For high-risk plugin systems where a bad plugin could crash the host CLI or corrupt user data, the output must include explicit error-handling contracts and require human review before publication.

Do not use this prompt when you lack source access or when the plugin system exists only as a design document without a working implementation to validate against. If you are speculating about a plugin architecture that has not been built, the generated reference will be untestable and likely incorrect. Similarly, avoid this prompt if you cannot provide a reference plugin implementation; without a concrete example, the model cannot verify that the documented contract matches what the loader actually expects. For purely conceptual plugin designs, start with an architecture decision record prompt instead, and return to this prompt only after you have working code and a reference plugin that loads successfully.

PRACTICAL GUARDRAILS

Use Case Fit

Where the CLI Plugin and Extension Reference Prompt delivers value and where it falls short. Use these cards to decide if this prompt fits your current documentation task.

01

Good Fit: Stable Plugin Interfaces

Use when: you have a defined plugin API, lifecycle hooks, or extension points that are versioned and stable. The prompt excels at generating structured interface specs, installation paths, and contract documentation from source annotations or interface definitions. Guardrail: Pin the prompt to a specific API version and require it to flag any undocumented or experimental surfaces it encounters.

02

Bad Fit: Rapidly Changing Internal APIs

Avoid when: the plugin interface is under active development with daily breaking changes. The prompt will produce documentation that drifts within hours, creating a maintenance burden and misleading plugin developers. Guardrail: Gate this prompt behind a CI check that compares generated docs against current interface signatures and blocks publication if drift exceeds a threshold.

03

Required Input: Plugin Loading Code

Risk: Without access to the actual plugin discovery and loading code, the prompt hallucinates installation paths, file naming conventions, and discovery mechanisms. Guardrail: Provide the plugin loader source, manifest schema, and at least one reference plugin implementation as grounded context. Validate generated installation instructions against a real plugin load test.

04

Required Input: Lifecycle Hook Signatures

Risk: Missing or vague lifecycle hook documentation leads plugin developers to implement incorrect function signatures, causing silent failures at runtime. Guardrail: Supply the exact hook function signatures, execution order, threading model, and error handling expectations. The prompt must produce a per-hook contract table that can be validated against the hook registration code.

05

Operational Risk: Version Compatibility Matrix

Risk: Plugin developers target the wrong CLI version, leading to broken integrations and support load. The prompt may omit version constraints or compatibility ranges. Guardrail: Require the prompt to generate an explicit version compatibility matrix mapping plugin API versions to CLI versions. Validate this matrix against actual version check logic in the plugin loader.

06

Operational Risk: Example Plugin Drift

Risk: Example plugins in the documentation stop working as the interface evolves, eroding developer trust. Guardrail: Treat example plugins as test artifacts. Run them in CI against the current CLI version. If an example fails, block the documentation publish and flag the specific breaking change.

PROMPT PLAYBOOK

Copy-Ready Prompt Template

A copy-pasteable prompt template for generating a complete CLI plugin developer reference from source code and plugin definitions.

This template is designed to ingest your plugin interface source code, configuration schemas, and any existing developer documentation to produce a comprehensive plugin reference. It forces the model to document the contract—installation paths, API surfaces, lifecycle hooks, and discovery mechanisms—rather than just describing the plugin in prose. Replace every square-bracket placeholder with your specific code, schemas, and constraints before use.

text
You are a technical writer for a CLI platform team. Your task is to produce a complete plugin and extension developer reference from the provided source code and plugin definitions.

## INPUT
- Plugin interface source code:
[PLUGIN_INTERFACE_SOURCE_CODE]

- Plugin manifest or configuration schema:
[PLUGIN_CONFIG_SCHEMA]

- Example plugin implementations (optional):
[EXAMPLE_PLUGIN_CODE]

- Existing developer docs (optional):
[EXISTING_DEV_DOCS]

## OUTPUT SCHEMA
Return a single JSON object with the following structure:
{
  "plugin_reference": {
    "overview": "string describing the plugin system's purpose and architecture",
    "installation_paths": [
      {
        "path": "string (e.g., ~/.cli/plugins, $CLI_PLUGIN_DIR)",
        "priority": "number (load order, lower = higher priority)",
        "description": "string"
      }
    ],
    "discovery_mechanism": {
      "method": "string (e.g., directory scan, manifest file, registry)",
      "description": "string",
      "configuration_required": "boolean"
    },
    "plugin_interface": {
      "required_exports": [
        {
          "name": "string (function, class, or variable name)",
          "type": "string (function, class, variable)",
          "signature": "string",
          "description": "string",
          "required": "boolean"
        }
      ],
      "optional_exports": [
        {
          "name": "string",
          "type": "string",
          "signature": "string",
          "description": "string"
        }
      ]
    },
    "lifecycle_hooks": [
      {
        "hook_name": "string",
        "trigger": "string (when the hook fires)",
        "arguments": "string (arguments passed to the hook)",
        "expected_return": "string",
        "description": "string"
      }
    ],
    "version_compatibility": {
      "plugin_api_version": "string",
      "minimum_cli_version": "string",
      "deprecated_versions": ["string"],
      "version_negotiation": "string (how plugins declare and check compatibility)"
    },
    "error_handling": {
      "plugin_load_failures": "string (what the CLI does when a plugin fails to load)",
      "runtime_errors": "string (how plugin errors are surfaced to users)",
      "isolation_guarantees": "string (process isolation, memory, crash boundaries)"
    },
    "example_plugin": {
      "code": "string (a minimal but complete working plugin)",
      "explanation": "string (walkthrough of the example)"
    }
  }
}

## CONSTRAINTS
- Document every required and optional export found in the plugin interface source code.
- If the source code defines a version constant or compatibility check, include it in version_compatibility.
- The example_plugin.code must be syntactically correct and runnable given the documented interface.
- If any field cannot be determined from the provided source, set its value to null and add a note in the description.
- Do not invent plugin hooks, exports, or behaviors not present in the source code.
- Use the exact function signatures and type names from the source code.

## RISK_LEVEL
Medium. Plugin documentation errors can cause integration failures for downstream developers. A human reviewer must verify the documented interface against the actual source code before publication.

After pasting this template, replace each placeholder with your actual source code and schemas. The [PLUGIN_INTERFACE_SOURCE_CODE] placeholder should contain the exact interface file that plugin authors must implement—typically a base class, a set of function signatures, or a protocol definition. The [PLUGIN_CONFIG_SCHEMA] should include your manifest format, whether it's a JSON schema, a YAML structure, or a Python setup.cfg entry point definition. If you have working example plugins, include them in [EXAMPLE_PLUGIN_CODE] to ground the model's output in real patterns. Run the output through a JSON schema validator before accepting it, and always diff the documented exports against the source interface to catch omissions.

IMPLEMENTATION TABLE

Prompt Variables

Each placeholder required by the CLI Plugin and Extension Reference Prompt, with concrete examples and actionable validation guidance for wiring into a documentation generation harness.

PlaceholderPurposeExampleValidation Notes

[PLUGIN_SOURCE_CODE]

Path or content of the plugin's main source file defining the interface

src/plugins/auth_provider.go

Parse check: file must exist and contain an exported interface or class definition. If content is provided directly, validate it is non-empty and compiles.

[PLUGIN_MANIFEST]

Plugin manifest or package descriptor declaring metadata and entry points

plugin.yaml or package.json

Schema check: must include name, version, and main entry point fields. Validate against the expected manifest schema for the target platform.

[INSTALLATION_PATH_CONVENTION]

Documented convention for where plugins are installed and discovered

$HOME/.cli/plugins or /etc/cli/plugins.d

Path check: verify the documented path matches the actual discovery mechanism in the CLI source. Test with a dummy plugin placed at the path.

[LIFECYCLE_HOOKS_LIST]

Explicit list of lifecycle hooks the plugin system supports

onInit, onExecute, onShutdown, onValidate

Completeness check: extract all hook invocations from the CLI host source and confirm every hook is documented. Flag any hooks found in source but missing from the list.

[API_CONTRACT_SCHEMA]

Interface or protocol definition the plugin must implement

type AuthPlugin interface { Authenticate(ctx, creds) (Token, error) }

Schema check: validate that the documented interface matches the actual interface in source code. Check method signatures, parameter types, and return types for parity.

[EXAMPLE_PLUGIN_CODE]

A minimal but complete working plugin implementation

A 40-line Python plugin that implements the auth provider interface

Build check: the example must compile or execute successfully against the current plugin SDK version. Test in CI to prevent example drift.

[VERSION_COMPATIBILITY_MATRIX]

Mapping of plugin API versions to compatible CLI host versions

Plugin API v2 supports CLI >= 3.1.0, < 4.0.0

Consistency check: verify the documented compatibility ranges match the version constraint logic in the plugin loader source. Test loading a plugin at each boundary version.

[DISCOVERY_MECHANISM_DESCRIPTION]

Description of how the CLI discovers and loads plugins at runtime

Scans $PLUGIN_PATH for .so files, validates manifest, registers hooks

Behavior check: trace the actual discovery code path and confirm the documented steps match the implementation order. Test with plugins in expected and unexpected locations.

PROMPT PLAYBOOK

Implementation Harness Notes

How to wire the CLI Plugin and Extension Reference Prompt into a documentation pipeline with validation and retry logic.

The CLI Plugin and Extension Reference Prompt is designed to be embedded in a documentation generation pipeline, not used as a one-off chat interaction. The harness must supply structured inputs—plugin interface definitions, lifecycle hook signatures, installation paths, and version compatibility matrices—and validate the generated reference against the actual plugin loading code. This section covers the integration points, validation gates, and retry logic needed to make the prompt reliable in production.

Wire the prompt into a pipeline that first extracts the plugin contract from source code. For a Go CLI using a plugin interface, parse the interface definition, exported methods, and any registration or discovery mechanism. Feed these into the prompt as [INPUT] along with a [CONTEXT] block containing the CLI version, supported plugin API versions, and known compatibility constraints. The prompt should produce a structured reference document with sections for interface specs, lifecycle hooks, installation paths, and example plugins. After generation, run a schema validator that checks the output against a defined [OUTPUT_SCHEMA]—verify that every documented method signature matches the parsed source interface, that all lifecycle hooks (init, execute, cleanup, shutdown) are present, and that installation paths reference real filesystem conventions. If validation fails, log the specific missing or mismatched fields and trigger a retry with the validation errors appended to the [CONSTRAINTS] block.

For retry logic, implement a two-pass approach. On the first pass, use a capable model (Claude 3.5 Sonnet or GPT-4o) with the full prompt template. If the schema validator returns errors, construct a repair prompt that includes the original output, the validation error list, and an instruction to fix only the flagged issues while preserving the rest of the document. Limit retries to two attempts; if the output still fails validation, route it to a human review queue with the validation report attached. Log every generation attempt—model used, token counts, validation pass/fail status, and retry count—so you can track prompt drift over time. For CLI tools with multiple plugins, batch the generation per plugin interface and run validations in parallel to keep the pipeline fast.

When the prompt output passes validation, inject it into your documentation site build. Add a drift detection step that runs weekly: re-parse the plugin source code, regenerate the reference, and diff it against the published version. Flag any new methods, changed signatures, or deprecated hooks for review. This keeps the plugin reference synchronized with the actual codebase without requiring manual audits. Avoid using this prompt for plugins with unstable or undocumented internal APIs—if the source code lacks clear interface boundaries, the generated reference will be speculative and should be marked as draft with a human-review gate before publication.

IMPLEMENTATION TABLE

Expected Output Contract

The structured JSON object the prompt must return. Validate every field before accepting the output into a downstream documentation pipeline or plugin registry.

Field or ElementType or FormatRequiredValidation Rule

plugin_name

string (kebab-case)

Must match regex ^[a-z][a-z0-9-]*[a-z0-9]$ and be unique within the registry

version_compatibility

object

Must contain min_version and max_version strings in semver format; max_version can be null for unbounded

interface_spec

object

Must include hooks (array of hook names), config_schema (valid JSON Schema object), and capabilities (array of capability strings)

installation

object

Must contain method (enum: npm, pip, binary, git, local), path_or_package (string), and post_install_steps (array of strings, can be empty)

lifecycle_hooks

array of objects

Each object must have hook (string matching interface_spec.hooks), phase (enum: pre, post, on_error), and handler (string path to executable or function)

discovery_metadata

object

Must include keywords (array of strings, min 1), description (string, 50-200 chars), and author (string)

example_plugin_path

string (relative path)

If present, must point to a valid example directory within the plugin source; validated by checking path existence in plugin archive

deprecation_notice

object or null

If not null, must contain since_version (semver string), replacement_plugin (string or null), and migration_guide_url (valid URL or null)

PRACTICAL GUARDRAILS

Common Failure Modes

What breaks first when generating CLI plugin references and how to guard against it.

01

Interface Drift from Implementation

What to watch: The prompt generates plugin interface documentation that looks correct but doesn't match the actual plugin loading code. Method signatures, hook names, or return types may be hallucinated rather than extracted from source. Guardrail: Always ground the prompt against actual plugin interface source files. Run a validation step that compares documented method signatures against the real interface definitions using AST parsing or reflection.

02

Missing Lifecycle Hooks

What to watch: The prompt documents the obvious initialization and execution hooks but omits less common lifecycle methods like cleanup, validation, configuration reload, or shutdown hooks. Plugin developers relying on the reference will miss critical integration points. Guardrail: Provide the prompt with a checklist of expected lifecycle phases from the plugin framework specification. After generation, diff the documented hooks against the framework's hook registry to catch omissions.

03

Version Compatibility Confusion

What to watch: The prompt conflates API versions, producing documentation that mixes v1 and v2 plugin interfaces, deprecated methods with current ones, or incorrect minimum version requirements. Plugin developers following the reference will target the wrong API surface. Guardrail: Explicitly pass the target version and a changelog of breaking changes as input context. Add a post-generation check that flags any method or type not present in the specified version's interface definition.

04

Example Plugin Code That Doesn't Compile

What to watch: The prompt generates example plugin implementations with incorrect imports, wrong type annotations, missing required method overrides, or syntax errors in the target language. These examples mislead developers and erode trust in the documentation. Guardrail: Extract example code blocks and run them through a compiler or static analyzer for the target language. Flag any example that fails type checking or references undefined symbols before publication.

05

Undocumented Error Contracts

What to watch: The prompt documents happy-path plugin behavior but omits error handling contracts: what exceptions plugins may throw, which error codes the host expects, how error messages propagate, and what happens on plugin load failure. Guardrail: Provide the prompt with the plugin framework's error handling source code or exception hierarchy. Add a dedicated error handling section requirement to the output schema and validate that every documented method includes its error contract.

06

Discovery Mechanism Misrepresentation

What to watch: The prompt invents plugin discovery paths, manifest formats, or registration mechanisms that don't match the actual plugin loading implementation. Plugin developers will place files in wrong directories or use incorrect manifest schemas. Guardrail: Ground discovery documentation against the actual plugin loader source code. Test documented discovery paths by attempting to load a minimal plugin from each documented location and verifying the host discovers it correctly.

IMPLEMENTATION TABLE

Evaluation Rubric

Score the generated plugin reference against these criteria before publishing. Each row targets a specific failure mode common in interface documentation derived from code.

CriterionPass StandardFailure SignalTest Method

Interface Contract Coverage

Every exported interface, type, and lifecycle hook from [PLUGIN_SOURCE] is documented with its full signature.

Missing hooks, undocumented exported types, or stale method signatures.

Parse [PLUGIN_SOURCE] AST to extract exports; diff against documented interfaces in [OUTPUT]. Count of undocumented exports must be zero.

Version Compatibility Matrix

Compatibility table maps every documented interface to the exact plugin API version range where it is valid.

Missing version ranges, 'all versions' placeholder without evidence, or documented interfaces that don't exist in the stated version.

Cross-reference each documented interface against git tags or versioned API specs. Flag any interface with no matching version evidence.

Installation Path Accuracy

Every documented installation path (plugin directory, config file, environment variable) matches the actual discovery mechanism in [LOADER_SOURCE].

Path that doesn't exist in loader code, missing required permissions note, or incorrect precedence order.

Trace discovery logic in [LOADER_SOURCE]; compare each documented path against loader's actual search order. Flag mismatches.

Example Plugin Correctness

Every example plugin in the reference compiles, loads, and exercises the documented interface without modification.

Example uses deprecated APIs, missing imports, incorrect lifecycle hook signatures, or fails against current plugin SDK.

Extract example code blocks; run compilation and loading test against [PLUGIN_SDK_VERSION]. Any failure is a blocking fail.

Error Handling Documentation

Every documented interface includes expected error conditions, error types, and recovery guidance where applicable.

Interface documented with no error section, generic 'throws Exception' without specifics, or error guidance that contradicts actual error handling in source.

For each documented interface, check [PLUGIN_SOURCE] for throw/return error paths. Flag interfaces with undocumented error conditions.

Lifecycle Hook Sequencing

Documentation specifies the exact order of lifecycle hook invocation, including parallelism guarantees and blocking behavior.

Missing sequence diagram or ordered list, incorrect ordering relative to [LIFECYCLE_SOURCE], or undocumented concurrency constraints.

Extract hook invocation order from [LIFECYCLE_SOURCE]; compare against documented sequence. Any ordering mismatch is a fail.

Configuration Schema Validation

Every configuration key accepted by the plugin system is documented with type, default, required status, and validation rule.

Undocumented config keys found in source, documented keys with wrong types, or missing default values that cause nil-pointer risks.

Parse config schema from [CONFIG_SOURCE]; diff against documented keys. Flag missing keys, type mismatches, and missing defaults.

Deprecation and Migration Coverage

All deprecated interfaces include deprecation version, removal timeline, replacement interface, and migration example.

Deprecated interface documented without replacement, missing removal version, or migration example that references another deprecated API.

Scan [PLUGIN_SOURCE] for deprecation annotations; verify each has complete deprecation documentation in [OUTPUT]. Flag incomplete entries.

ADAPTATION OPTIONS

Adapt This Prompt

How to adapt

Use the base prompt with a single plugin interface example and lighter validation. Focus on getting the structure right before scaling to multiple plugin types.

  • Remove the [PLUGIN_REGISTRY_SCHEMA] constraint and let the model infer the interface shape from [PLUGIN_SOURCE_CODE].
  • Replace [OUTPUT_SCHEMA] with a simple markdown template: ## Interface, ## Installation, ## Lifecycle Hooks, ## Example Plugin.
  • Drop the version compatibility matrix requirement; accept a single ## Compatibility section with a prose note.

Watch for

  • The model inventing lifecycle hooks not present in [PLUGIN_SOURCE_CODE].
  • Missing error handling documentation for plugin load failures.
  • Overly generic example plugins that don't exercise the actual interface.
Prasad Kumkar

About the author

Prasad Kumkar

CEO & MD, Inference Systems

Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.

His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.