Fakey Testing Provider

fakey is a deterministic fake agent CLI bundled with SASE. Its first-class FakeyProvider uses the same registry, model selection, subprocess streaming, interrupt, usage, and retry plumbing as real providers, making it useful for reproducible launch and failure tests. It never calls a model and should not be used for production coding work.

Quick Start

The default scenario succeeds immediately:

printf 'hello\n' | fakey

Select fakey for one SASE launch with either model tier:

%model:fakey-large
Exercise the launch path.

The provider maps large to fakey-large and small to fakey-small. It is deliberately the last autodetection candidate because the executable is always installed with SASE; prefer explicit selection.

Fakey models are not offered in the ACE model picker or the %model completion menu — it exists only for testing, so it is hidden from user-facing model selection surfaces. It remains fully registered and routable: the explicit spellings above (%model:fakey-large, sase run -m fakey-large) and %model:fakey/fakey-large all still work, and the picker's Custom... entry accepts them by hand. There is no implicit @fakey_coder role alias; if you deliberately configure model_aliases.custom.fakey_coder, it appears in the ACE Launch Control (,m) as an ordinary user alias.

Fakey is also intentionally absent from sase agent-cli inventories and the SASE Admin Center's Updates → Agent CLIs list. It is bundled for internal testing rather than independently installed or updated, but explicit execution, provider routing, and sase doctor diagnostics remain available.

Scenario Selection and Precedence

Scenario settings are layered from least to most specific:

1. Built-in success defaults.
2. Individual environment knobs.
3. FAKEY_SCENARIO, a YAML path or bundled @name.
4. A fenced fakey YAML block embedded in the prompt.

For example:

Run a deterministic response.

```fakey
reply: embedded reply
usage: {input_tokens: 7, output_tokens: 3}
```

List bundled scenarios with fakey --list-scenarios. The bundled set includes @ok, @flaky, @flaky2, @crash, @hang, @slow, @capacity, and the long-streaming @demo. Use fakey --scenario @flaky --explain to print the resolved YAML without running it.

For a hermetic launch that still displays the requested real provider and model, set the execution-provider override:

FAKEY_SCENARIO=@demo SASE_LLM_EXEC_PROVIDER=fakey \
  sase run '%model:opus Exercise the launch path without a model call'

The agent metadata remains CLAUDE(opus) while exec_llm_provider: fakey records what actually ran.

Scenario Grammar

version: 1
reply: default success text
delay: 0
stream:
  chunk_delay: 0.05
usage:
  input_tokens: 7
  output_tokens: 3
attempts:
  - fail:
      message: model melted
      retryable: true
      exit_code: 1
      channel: stderr
    steps:
      - signal: /tmp/fakey-started
      - wait_for: { path: /tmp/fakey-release, timeout: 30 }
  - succeed:
      reply: second try worked

The attempt cursor persists in FAKEY_STATE_DIR; the final attempt repeats after the list is exhausted. A retryable failure emits FAKEY-RETRYABLE: <message>, while other failures emit FAKEY-FAIL: <message>. The provider's built-in retry config matches only the retryable marker, retries up to three times with no delay, and preserves workspace edits.

Steps support signal, wait_for, and sleep. Every wait_for has a timeout, and SIGTERM exits cleanly, which makes barrier-based tests deterministic without timing sleeps.

Environment Controls

Variable	Purpose
FAKEY_SCENARIO	Scenario path or bundled name such as @flaky
FAKEY_REPLY	One-line success reply override
FAKEY_FAIL_MESSAGE	One-line failure message
FAKEY_EXIT_CODE	Failure exit code
FAKEY_DELAY	Delay before the outcome
FAKEY_FAIL_TIMES	Fail this many invocations, then succeed
FAKEY_STATE_DIR	Attempt cursor and invocation-<n>.json recording directory
SASE_LLM_EXEC_PROVIDER	Runtime-only provider override; set to fakey for hermetic real-model launches
SASE_FAKEY_PATH	Override the provider's fakey executable
SASE_FAKEY_LARGE_ARGS	Extra provider args for the large tier
SASE_FAKEY_SMALL_ARGS	Extra provider args for the small tier
SASE_LLM_LARGE_ARGS	Provider-neutral large-tier args; takes precedence
SASE_LLM_SMALL_ARGS	Provider-neutral small-tier args; takes precedence

Each invocation record contains argv, prompt, selected environment, resolved scenario and attempt, model, effort, and outcome. This makes provider wiring assertions possible without mocking the subprocess.

Testing Retries

For an interactive retry smoke test, set an isolated state directory and launch the bundled flaky scenario:

export FAKEY_STATE_DIR="$(mktemp -d)"
export FAKEY_SCENARIO=@flaky
sase run -m fakey-large 'Exercise retry handling'

The first invocation fails with FAKEY-RETRYABLE; SASE's provider defaults retry immediately, and the second invocation succeeds. Inspect $FAKEY_STATE_DIR/invocation-*.json to verify both prompts, selected model, and outcomes. For tests, prefer a temporary scenario file and signal/wait_for barriers so assertions can freeze and release exact pipeline states without depending on wall-clock sleeps.

The integration-test harness in tests/fakey/harness.py drives the real run_execution_loop and fakey subprocess. A typical executor test creates a FakeyRetryHarness, calls use_scenario() with a retryable failure followed by successful_attempt(), starts run_in_background(), and waits on wait_for_retry_state() before releasing its barrier. The harness isolates the SASE home, artifacts, scenario state, and retry configuration for every test.

Visual retry tests use the same harness with expose_to_agent_loader=True. That option writes the run under the isolated production artifact layout so load_agents_from_disk_with_state reads the real agent_meta.json, retry_state.json, attempts, and done.json. Use hold_retry_wait() or a scenario barrier to freeze the desired state, then normalize_visual_timestamps() before capturing a PNG against the pinned visual clock. Always release the barrier, finish the execution handle, and assert the Agents tab reloads to its terminal state.