Gaze Analyzer Protocol Specification

Version: 1.1.0 Transport: JSON-RPC 2.0 over stdin/stdout

Overview

The Gaze Analyzer Protocol enables external language analyzers to provide side effect detection, complexity analysis, and coverage data to Gaze. Gaze spawns the analyzer as a subprocess, communicates via JSON-RPC 2.0 over stdin/stdout, and uses the responses to compute CRAP scores, GazeCRAP scores, quadrant classifications, and fix strategies.

This protocol follows the same transport model as the Language Server Protocol (LSP): line-delimited JSON over stdin/stdout, with stderr reserved for diagnostics.

Lifecycle

gaze crap --analyzer snake-eyes ./src
|
+-- 1. Discover analyzer binary (CLI flag / .gaze.yaml / PATH)
+-- 2. Spawn: snake-eyes --stdio
+-- 3. initialize --> capabilities handshake
+-- 4. discover --> find source + test files (optional)
+-- 5. analyze --> detect side effects per function
+-- 6. complexity --> cyclomatic complexity per function
+-- 7. coverage --> line coverage per function
+-- 8. test_mapping --> map assertions to effects (optional)
+-- 9. classify_signals --> classification signals (optional)
+-- 10. shutdown --> clean exit
+-- 11. Gaze computes CRAP, GazeCRAP, quadrants, fix strategies

Discovery

Gaze finds analyzer binaries using a three-tier mechanism:

CLI flag: --analyzer <binary> -- explicit binary name or path
Config file: .gaze.yaml analyzers.<language>.command
PATH convention: gaze-analyzer-<language> on PATH

The --language flag determines which language key to look up in tiers 2 and 3. When --analyzer is specified directly, --language is optional.

Message Format

Request

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "analyze",
  "params": {
    "root_path": "/path/to/project",
    "patterns": ["./..."]
  }
}

Response (success)

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": { ... }
}

Response (error)

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32603,
    "message": "Internal error",
    "data": "optional details"
  }
}

Error Codes

Standard JSON-RPC 2.0 error codes:

Code	Meaning
-32700	Parse error
-32600	Invalid request
-32601	Method not found
-32602	Invalid params
-32603	Internal error

Methods

Required Methods

Every analyzer must implement these 5 methods.

`initialize`

Handshake method. Must be the first method called. Returns the analyzer's capabilities and identity.

Timeout: 30 seconds

Request params:

{
  "root_path": "/absolute/path/to/project",
  "config": {}
}

Field	Type	Required	Description
`root_path`	string	yes	Absolute path to the project root
`config`	object	no	Analyzer-specific config from `.gaze.yaml`

Response result:

{
  "capabilities": {
    "discover": true,
    "test_mapping": true,
    "classify_signals": false,
    "streaming": false
  },
  "protocol_version": "1.1.0",
  "analyzer_name": "snake-eyes",
  "language": "python",
  "language_version": "3.12.0"
}

Field	Type	Description
`capabilities.discover`	boolean	Supports the `discover` method
`capabilities.test_mapping`	boolean	Supports the `test_mapping` method
`capabilities.classify_signals`	boolean	Supports the `classify_signals` method
`capabilities.streaming`	boolean	Supports the `analyze/stream` method
`protocol_version`	string	Protocol version (semver)
`analyzer_name`	string	Human-readable analyzer name
`language`	string	Primary language (e.g., "python", "rust")
`language_version`	string	Runtime/compiler version (optional)

`analyze`

Detect side effects for all functions in the project.

Timeout: 5 minutes

Request params:

{
  "root_path": "/path/to/project",
  "patterns": ["./..."]
}

Response result:

{
  "functions": [
    {
      "name": "divide",
      "package": "math_utils",
      "file": "math_utils/ops.py",
      "line": 20,
      "side_effects": [
        {
          "type": "ReturnValue",
          "description": "returns division result",
          "location": "math_utils/ops.py:25:5",
          "target": "result",
          "detail": {
            "python_type": "float"
          },
          "classification": {
            "label": "contractual",
            "confidence": 90
          }
        },
        {
          "type": "ErrorReturn",
          "description": "raises ZeroDivisionError",
          "location": "math_utils/ops.py:22:9",
          "target": "ZeroDivisionError",
          "detail": {
            "exception_class": "ZeroDivisionError"
          },
          "classification": {
            "label": "contractual",
            "confidence": 85
          }
        }
      ]
    }
  ]
}

Side Effect Types

Analyzers map their language concepts to Gaze's universal taxonomy of 48 canonical side effect types. Each type belongs to exactly one priority tier (P0–P4). Unknown types default to P4 tier with a warning.

P0 — Must Detect (6 types)

Type	Tier	Definition	Go Mapping	Python Mapping
`ReturnValue`	P0	Function returns a value	`return x`	`return x`
`ErrorReturn`	P0	Function signals an error	`return err`	`raise Exception`
`SentinelError`	P0	Named error constant/value callers match against	`var ErrFoo = errors.New(...)`	`class FooError(Exception)`
`ReceiverMutation`	P0	Mutates the receiver/self	`s.field = x`	`self.field = x`
`PointerArgMutation`	P0	Mutates a parameter passed by reference	`*arg = x`	mutable arg mutation
`ErrorSignal`	P0	Language-neutral error signaling mechanism	`return err`	`raise`, `throw`

P1 — High Value (11 types)

Type	Tier	Definition	Go Mapping	Python Mapping
`SliceMutation`	P1	Mutates a dynamic array/list parameter	`slice[i] = x`	`list[i] = x`
`MapMutation`	P1	Mutates a dictionary/hash map parameter	`m[k] = v`	`dict[k] = v`
`GlobalMutation`	P1	Writes to module-level / global state	`pkg.Var = x`	module-level write
`WriterOutput`	P1	Writes to an injected output stream	`w.Write(data)`	`writer.write(data)`
`HTTPResponseWrite`	P1	Writes to an HTTP response object	`w.WriteHeader(200)`	`response.write(data)`
`ChannelSend`	P1	Sends a value to a concurrency channel/queue	`ch <- v`	`queue.put(v)`
`ChannelClose`	P1	Closes a concurrency channel/queue	`close(ch)`	`queue.close()`
`DeferredReturnMutation`	P1	Mutates a return value in a deferred/finally block	`defer func() { err = wrap(err) }()`	`finally: result = ...`
`GeneratorYield`	P1	Yields a value from a generator/iterator	(no direct equivalent)	`yield x`
`ContainerMutation`	P1	Mutates a generic container parameter (set, deque, etc.)	(no direct equivalent)	`set.add(x)`, `deque.append(x)`
`StreamOutput`	P1	Writes to a generic output stream	`stream.Write(data)`	`stream.write(data)`

P2 — Important (16 types)

Type	Tier	Definition	Go Mapping	Python Mapping
`FileSystemWrite`	P2	Writes to filesystem	`os.WriteFile(...)`	`open().write()`
`FileSystemDelete`	P2	Deletes a filesystem entry	`os.Remove(...)`	`os.remove(...)`
`FileSystemMeta`	P2	Modifies filesystem metadata (permissions, timestamps)	`os.Chmod(...)`	`os.chmod(...)`
`DatabaseWrite`	P2	Writes to a database	`db.Exec(...)`	`cursor.execute(...)`
`DatabaseTransaction`	P2	Manages a database transaction	`tx.Commit()`	`conn.commit()`
`GoroutineSpawn`	P2	Spawns a concurrent task	`go func(){}()`	`threading.Thread(...)`
`Panic`	P2	Unrecoverable error / panic / abort	`panic(msg)`	`sys.exit(1)`
`CallbackInvocation`	P2	Invokes a function parameter (callback, closure)	`fn()`	`callback()`
`LogWrite`	P2	Writes to a logging system	`log.Printf(...)`	`logging.info(...)`
`ContextCancellation`	P2	Cancels a context or cancellation token	`cancel()`	`event.set()`
`AsyncGeneratorYield`	P2	Yields from an async generator	(no direct equivalent)	`async def gen(): yield x`
`MetaprogrammingMutation`	P2	Mutates program structure at runtime	(no direct equivalent)	`setattr(obj, name, val)`
`DescriptorEffect`	P2	Side effect via descriptor protocol	(no direct equivalent)	`__set__`, `__delete__`
`ResourceManagement`	P2	Acquires or releases an external resource	`file.Close()`	`__enter__`/`__exit__`
`ImportSideEffect`	P2	Module import triggers observable side effects	`import _ "pkg"`	`import module` (with side effects)
`MonkeyPatch`	P2	Runtime replacement of functions/methods	(no direct equivalent)	`module.func = mock`

P3 — Nice to Have (9 types)

Type	Tier	Definition	Go Mapping	Python Mapping
`StdoutWrite`	P3	Writes to standard output	`fmt.Println(...)`	`print(...)`
`StderrWrite`	P3	Writes to standard error	`fmt.Fprintln(os.Stderr, ...)`	`print(..., file=sys.stderr)`
`EnvVarMutation`	P3	Modifies environment variables	`os.Setenv(k, v)`	`os.environ[k] = v`
`MutexOp`	P3	Acquires or releases a mutex/lock	`mu.Lock()`	`lock.acquire()`
`WaitGroupOp`	P3	Operates on a synchronization barrier	`wg.Add(1)`	`barrier.wait()`
`AtomicOp`	P3	Performs an atomic memory operation	`atomic.AddInt64(...)`	(no direct equivalent)
`TimeDependency`	P3	Depends on wall-clock time	`time.Now()`	`time.time()`
`ProcessExit`	P3	Terminates the process	`os.Exit(1)`	`sys.exit(1)`
`RecoverBehavior`	P3	Recovers from a panic/exception	`recover()`	`except Exception:`

P4 — Exotic (6 types)

Type	Tier	Definition	Go Mapping	Python Mapping
`ReflectionMutation`	P4	Mutates state via reflection	`reflect.ValueOf(&x).Elem().Set(...)`	`setattr(obj, name, val)`
`UnsafeMutation`	P4	Mutates state via unsafe pointer operations	`unsafe.Pointer`	`ctypes` pointer writes
`CgoCall`	P4	Calls foreign function interface (FFI)	`C.function()`	`ctypes.cdll.func()`
`FinalizerRegistration`	P4	Registers a finalizer/destructor callback	`runtime.SetFinalizer(...)`	`weakref.finalize(...)`
`SyncPoolOp`	P4	Operates on an object pool	`sync.Pool.Get/Put`	(no direct equivalent)
`ClosureCaptureMutation`	P4	Mutates a variable captured by a closure	captured var write	captured var write

Language-Neutral Aliases

The following aliases allow analyzers to use language-neutral names that resolve to the same canonical type:

Alias	Resolves To	Use When
`AsyncTaskSpawn`	`GoroutineSpawn`	Spawning async tasks, threads, coroutines
`AsyncMessageSend`	`ChannelSend`	Sending to queues, mailboxes, actors
`AsyncChannelClose`	`ChannelClose`	Closing queues, mailboxes, streams
`BarrierOp`	`WaitGroupOp`	Barriers, latches, countdown events
`PanicRecovery`	`RecoverBehavior`	Exception handling, panic recovery
`FFICall`	`CgoCall`	Foreign function interface calls (ctypes, napi, JNI)
`ObjectPoolOp`	`SyncPoolOp`	Object/connection pool operations
`DeferredMutation`	`DeferredReturnMutation`	Finally blocks, scope guards, RAII cleanup
`ArgumentMutation`	`PointerArgMutation`	Mutating parameters passed by reference
`ProcessTermination`	`Panic`	Process abort, unrecoverable errors
`SentinelErrorDecl`	`SentinelError`	Named error type/constant declarations

Aliases are accepted in analyze responses and resolve to the canonical type for scoring and classification. The full taxonomy is defined in internal/taxonomy/types.go.

The `detail` Field

Each side effect in the analyze response may include an optional detail object containing language-specific metadata. This field is opaque to Gaze — it is passed through to JSON output and AI report pipelines without interpretation. Gaze does not use detail for scoring, classification, or CRAP computation.

Use detail to provide context that helps AI report generators or downstream tooling understand the effect in language-specific terms (e.g., exception class names, decorator metadata, type annotations).

Size guidance: Keep detail payloads small — under 1KB per effect. Large payloads increase JSON output size and may degrade AI report quality. Include only the metadata needed for downstream interpretation.

Classification

Each side effect may include a classification object:

Field	Type	Description
`label`	string	`"contractual"`, `"incidental"`, or `"ambiguous"`
`confidence`	integer	0-100 confidence score

When classification is null, Gaze uses default classification based on the effect type's tier.

Language-neutral side effect type aliases: External analyzers may use either Go-specific type names (e.g., GoroutineSpawn, ChannelSend, CgoCall) or language-neutral aliases (e.g., AsyncTaskSpawn, AsyncMessageSend, FFICall). The aliases map to the same string values as the Go-specific names: AsyncTaskSpawn = GoroutineSpawn, AsyncMessageSend = ChannelSend, AsyncChannelClose = ChannelClose, BarrierOp = WaitGroupOp, PanicRecovery = RecoverBehavior, FFICall = CgoCall, ObjectPoolOp = SyncPoolOp.

`analyze/stream` (optional)

Streaming alternative to the batch analyze method. When the analyzer declares capabilities.streaming: true in the initialize response, Gaze calls analyze/stream instead of analyze.

Timeout: 5 minutes

Request params: Same as analyze.

Response format: Instead of a single JSON-RPC response, the analyzer writes one JSON object per line (JSONL) to stdout. Each line represents one AnalyzedFunction — the same schema as the functions array elements in the batch response.

{"name":"add","package":"math_utils","file":"math_utils/ops.py","line":1,"side_effects":[]}
{"name":"multiply","package":"math_utils","file":"math_utils/ops.py","line":10,"side_effects":[{"type":"ReturnValue","description":"returns result","location":"ops.py:12:5","target":"result"}]}
{"name":"divide","package":"math_utils","file":"math_utils/ops.py","line":20,"side_effects":[{"type":"ReturnValue","description":"returns result","location":"ops.py:25:5","target":"result"},{"type":"ErrorReturn","description":"raises ZeroDivisionError","location":"ops.py:22:9","target":"ZeroDivisionError"}]}

Error handling: If a line contains invalid JSON, Gaze stops processing (fail-fast) and reports the error with the line number and content.

When to use streaming: Streaming is beneficial for large codebases (10K+ functions) where a single batch response would be multi-megabyte. For small codebases, the batch analyze method is simpler and sufficient.

`complexity`

Compute cyclomatic complexity for all functions.

Timeout: 5 minutes

Request params:

{
  "root_path": "/path/to/project",
  "patterns": ["./..."]
}

Response result:

{
  "functions": [
    {
      "name": "divide",
      "package": "math_utils",
      "file": "math_utils/ops.py",
      "line": 20,
      "complexity": 5
    }
  ]
}

Field	Type	Description
`name`	string	Function or method name
`package`	string	Package/module path
`file`	string	Source file path (relative or absolute)
`line`	integer	Line number of function declaration
`complexity`	integer	Cyclomatic complexity value

`coverage`

Produce per-function line coverage data. The analyzer is responsible for running tests and collecting coverage internally.

Timeout: 5 minutes

Request params:

{
  "root_path": "/path/to/project",
  "patterns": ["./..."]
}

Response result:

{
  "functions": [
    {
      "file": "math_utils/ops.py",
      "function": "divide",
      "start_line": 20,
      "end_line": 30,
      "covered_stmts": 0,
      "total_stmts": 10,
      "percentage": 0.0
    }
  ]
}

Field	Type	Description
`file`	string	Source file path
`function`	string	Function or method name
`start_line`	integer	Function declaration start line
`end_line`	integer	Function body end line
`covered_stmts`	integer	Number of statements covered by tests
`total_stmts`	integer	Total number of statements
`percentage`	number	Coverage percentage (0.0-100.0)

`shutdown`

Request the analyzer to shut down cleanly. The analyzer should finish any pending work and exit.

Timeout: 10 seconds

Request params: none (or null)

Response result: {}

After receiving the shutdown response, Gaze closes stdin and waits for the process to exit.

Optional Methods

These methods are declared via capabilities in the initialize response. Gaze only calls them when the corresponding capability is true.

`discover` (optional)

Find source and test files in the project. Reserved for future use -- currently not consumed by Gaze's provider interfaces.

Capability: discover

Request params:

{
  "root_path": "/path/to/project"
}

Response result:

{
  "source_files": ["math_utils/ops.py", "math_utils/helpers.py"],
  "test_files": ["tests/test_ops.py"],
  "framework": "pytest"
}

`test_mapping` (optional)

Map test assertions to side effects. When supported, this enables GazeCRAP scoring (contract coverage).

Capability: test_mapping

Request params:

{
  "root_path": "/path/to/project",
  "patterns": ["./..."]
}

Response result:

{
  "mappings": [
    {
      "test_function": "test_multiply",
      "test_file": "tests/test_ops.py",
      "assertion_location": "tests/test_ops.py:10",
      "assertion_type": "equality",
      "target_function": "multiply",
      "target_package": "math_utils",
      "side_effect_type": "ReturnValue",
      "confidence": 80
    }
  ]
}

Field	Type	Description
`test_function`	string	Test function name
`test_file`	string	Test file path
`assertion_location`	string	Source position of the assertion
`assertion_type`	string	Kind of assertion (e.g., "equality", "error_check")
`target_function`	string	Function under test
`target_package`	string	Package of the function under test
`side_effect_type`	string	Type of side effect being asserted on
`confidence`	integer	Mapping confidence (0-100)

`classify_signals` (optional)

Provide raw classification signals for Gaze's scoring engine. When supported, these signals are fed into classify.ComputeScore alongside Gaze's built-in signals.

Capability: classify_signals

Request params:

{
  "root_path": "/path/to/project",
  "patterns": ["./..."]
}

Response result:

{
  "signals": [
    {
      "function": "divide",
      "package": "math_utils",
      "side_effect_type": "ErrorReturn",
      "source": "docstring",
      "weight": 15,
      "reasoning": "docstring mentions ZeroDivisionError"
    }
  ]
}

Field	Type	Description
`function`	string	Function name
`package`	string	Package path
`side_effect_type`	string	Side effect type this signal relates to
`source`	string	Signal type (e.g., "docstring", "type_annotation", "decorator")
`weight`	integer	Numeric contribution to confidence score
`reasoning`	string	(optional) Explanation of why this signal was applied

Error Handling

Required method errors

When a required method (analyze, complexity, coverage) returns a JSON-RPC error, Gaze propagates the error and exits non-zero. The error message is displayed to the user.

Optional method errors

When an optional method (discover, test_mapping, classify_signals) returns an error, Gaze logs a warning to stderr and degrades gracefully:

discover error: no impact (not currently consumed)
test_mapping error: GazeCRAP is unavailable
classify_signals error: uses pre-classified effects from analyze

Process crashes

If the analyzer process exits unexpectedly (crash, segfault), Gaze detects the closed stdin/stdout pipes and returns an error with the process's stderr output for diagnostics.

Timeouts

Each method has a default timeout (30s for handshake methods, 5min for analysis methods). When the timeout expires, Gaze kills the subprocess and returns a timeout error.

Configuration

`.gaze.yaml`

analyzers:
  python:
    command: snake-eyes
    args: ["--stdio"]
  rust:
    command: /usr/local/bin/gaze-analyzer-rust
    args: ["--stdio", "--edition=2021"]

CLI Flags

Flag	Description
`--analyzer <binary>`	Explicit analyzer binary name or path
`--language <lang>`	Target language for config/PATH discovery

Building an Analyzer

To build a Gaze-compatible analyzer:

Accept --stdio flag: Read JSON-RPC requests from stdin, write responses to stdout, diagnostics to stderr.
Implement the 5 required methods: initialize, analyze, complexity, coverage, shutdown.
Declare capabilities: In the initialize response, set test_mapping: true if you can map assertions to effects (enables GazeCRAP).
Map to Gaze's taxonomy: Use Gaze's SideEffectType constants for the type field in analyze responses.
Follow naming convention: Name your binary gaze-analyzer-<language> for automatic PATH discovery.

Minimal Example (Python)

#!/usr/bin/env python3
"""Minimal Gaze analyzer for demonstration."""
import json
import sys

def handle(request):
    method = request["method"]
    rid = request["id"]

    if method == "initialize":
        return {"jsonrpc": "2.0", "id": rid, "result": {
            "capabilities": {"discover": False, "test_mapping": False, "classify_signals": False},
            "protocol_version": "1.1.0",
            "analyzer_name": "minimal-python",
            "language": "python"
        }}
    elif method == "analyze":
        return {"jsonrpc": "2.0", "id": rid, "result": {"functions": []}}
    elif method == "complexity":
        return {"jsonrpc": "2.0", "id": rid, "result": {"functions": []}}
    elif method == "coverage":
        return {"jsonrpc": "2.0", "id": rid, "result": {"functions": []}}
    elif method == "shutdown":
        return {"jsonrpc": "2.0", "id": rid, "result": {}}
    else:
        return {"jsonrpc": "2.0", "id": rid, "error": {
            "code": -32601, "message": f"Method not found: {method}"
        }}

for line in sys.stdin:
    request = json.loads(line.strip())
    response = handle(request)
    print(json.dumps(response), flush=True)
    if request["method"] == "shutdown":
        break

Testing Your Analyzer

Use Gaze's fake analyzer as a reference implementation: internal/protocol/testdata/fake_analyzer/main.go.

# Test with gaze crap
gaze crap --analyzer ./my-analyzer --language python ./src

# Test with JSON output (no AI adapter needed)
gaze report --analyzer ./my-analyzer --format=json ./src

FilesExpand file tree

protocol.md

Latest commit

History

protocol.md

File metadata and controls

Gaze Analyzer Protocol Specification

Overview

Lifecycle

Discovery

Message Format

Request

Response (success)

Response (error)

Error Codes

Methods

Required Methods

initialize

analyze

Side Effect Types

P0 — Must Detect (6 types)

P1 — High Value (11 types)

P2 — Important (16 types)

P3 — Nice to Have (9 types)

P4 — Exotic (6 types)

Language-Neutral Aliases

The detail Field

Classification

analyze/stream (optional)

complexity

coverage

shutdown

Optional Methods

discover (optional)

test_mapping (optional)

classify_signals (optional)

Error Handling

Required method errors

Optional method errors

Process crashes

Timeouts

Configuration

.gaze.yaml

CLI Flags

Building an Analyzer

Minimal Example (Python)

Testing Your Analyzer

`initialize`

`analyze`

The `detail` Field

`analyze/stream` (optional)

`complexity`

`coverage`

`shutdown`

`discover` (optional)

`test_mapping` (optional)

`classify_signals` (optional)

`.gaze.yaml`