bbdev Motia v0.17.x to 1.0-RC Migration

[shirohasuki]

Current State Summary

The bbdev project is a Python-only Motia application at bbdev/api/ with:

• 28 step files across 7 flows: verilator, compiler, firesim, marshal, sardine, palladium, workload
• Every flow follows the same API + Event step pair pattern:
  • API step (*_api_step.py): receives HTTP POST, calls context.emit(), then polls wait_for_result() in a loop
  • Event step (*_event_step.py): subscribes to a topic, runs a shell command via stream_run_logger(), writes result to state via check_result()
• 1 TypeScript config file: motia.config.ts (uses defineConfig with plugins)
• Dependencies: motia@0.17.14-beta.196 + 8 @motiadev/* plugin packages
• Utility modules: event_common.py, stream_run.py, path.py, port.py, search_workload.py
• Services layer: services/ directory with tool classes (not Motia steps, just helper code)

Migration Plan

Phase 1: Project Infrastructure

Task	Details
Create config.yaml	Define modules: RestApiModule, StateModule, QueueModule, PubSubModule, ExecModule (Python-only, using uv run motia dev --dir steps)
Create pyproject.toml	Add motia[otel], iii-sdk, pydantic>=2.0 as dependencies
Handle motia.config.ts	No stream auth is used — delete entirely
Handle package.json	Python-only project — delete (along with pnpm-lock.yaml, pnpm-workspace.yaml)
Delete old artifacts	Remove .motia/ directory, types.d.ts
Install iii engine	From https://iii.dev

Phase 2: Migrate 14 API Steps (HTTP triggers)

All API steps follow an identical pattern. The transformation is mechanical:

Before:

config = {
    "type": "api",
    "name": "Verilator Clean",
    "path": "/verilator/clean",
    "method": "POST",
    "emits": ["verilator.clean"],
    "flows": ["verilator"],
}

async def handler(req, context):
    body = req.get("body") or {}
    await context.emit({"topic": "verilator.clean", "data": {...}})
    while True:
        result = await wait_for_result(context)
        if result is not None:
            return result
        await asyncio.sleep(1)

After:

from motia import ApiRequest, ApiResponse, FlowContext, http

config = {
    "name": "Verilator Clean",
    "description": "clean build directory",
    "flows": ["verilator"],
    "triggers": [http("POST", "/verilator/clean")],
    "enqueues": ["verilator.clean"],
}

async def handler(request: ApiRequest, ctx: FlowContext) -> ApiResponse:
    body = request.body or {}
    await ctx.enqueue({"topic": "verilator.clean", "data": {...}})
    while True:
        result = await wait_for_result(ctx)
        if result is not None:
            return ApiResponse(status=result["status"], body=result["body"])
        await asyncio.sleep(1)

Key changes:

• "type": "api" removed, "method" + "path" move into http() trigger
• "emits" becomes "enqueues"
• context.emit() becomes ctx.enqueue()
• req.get("body") becomes request.body
• Return dict becomes ApiResponse(status=..., body=...)

Files (14 total):

• verilator/: 01_clean_api, 02_verilog_api, 03_build_api, 04_sim_api, 04_cosim_api, 05_run_api
• compiler/01_build_api
• firesim/: 01_buildbitstream_api, 02_infrasetup_api, 03_runworkload_api
• marshal/: 01_build_api, 02_launch_api
• sardine/01_run_api
• palladium/01_verilog_api
• workload/01_buidl_api

Phase 3: Migrate 14 Event Steps (Queue triggers)

Also mechanical:

Before:

config = {
    "type": "event",
    "name": "make clean",
    "subscribes": ["verilator.run", "verilator.clean"],
    "emits": ["verilator.verilog"],
    "flows": ["verilator"],
}

async def handler(data, context):
    ...
    await context.emit({"topic": "verilator.verilog", "data": {...}})

After:

from motia import FlowContext, queue

config = {
    "name": "make clean",
    "description": "clean build directory",
    "flows": ["verilator"],
    "triggers": [
        queue("verilator.run"),
        queue("verilator.clean"),
    ],
    "enqueues": ["verilator.verilog"],
}

async def handler(input_data: dict, ctx: FlowContext) -> None:
    ...
    await ctx.enqueue({"topic": "verilator.verilog", "data": {...}})

Key changes:

• "type": "event" removed
• "subscribes": [...] becomes triggers: [queue(...)] (multiple topics = multiple queue() calls)
• "emits" becomes "enqueues"
• context.emit() becomes ctx.enqueue()
• Handler params (data, context) become (input_data: dict, ctx: FlowContext)

Files (14 total):

• verilator/: 01_clean_event, 02_verilog_event, 03_build_event, 04_sim_event, 04_cosim_event
• compiler/01_build_event
• firesim/: 01_buildbitstream_event, 02_infrasetup_event, 03_runworkload_event
• marshal/: 01_build_event, 02_launch_event
• sardine/01_run_event
• palladium/01_verilog_event
• workload/01_build_event

Phase 4: Update Utility Modules

File	Changes
utils/event_common.py	context.state → ctx.state, context.trace_id → ctx.trace_id, context.logger → ctx.logger. These are shared helpers used by all steps — parameter naming must match new convention.
utils/stream_run.py	No changes needed — pure Python subprocess utility, no Motia API usage
utils/path.py	No changes needed
utils/port.py	No changes needed
utils/search_workload.py	No changes needed
services/*	No changes needed — no Motia API usage
types.d.ts	Delete — auto-generated by old Motia, no longer used

Phase 5: Cleanup

• Delete motia.config.ts, package.json, pnpm-lock.yaml, pnpm-workspace.yaml
• Delete types.d.ts
• Delete .motia/ directory
• Evaluate whether flake.nix needs updates for iii engine and new commands

Change Summary

Change	Count	Type
"type": "api" → http() trigger	14 files	Mechanical
"type": "event" → queue() trigger	14 files	Mechanical
context.emit() → ctx.enqueue()	~20 calls	Find-and-replace
"emits" → "enqueues"	28 configs	Find-and-replace
req.get("body") → request.body	14 API handlers	Mechanical
Return dict → ApiResponse(...)	14 API handlers	Mechanical
context.* → ctx.* in utils	2 files	Find-and-replace
New config.yaml	1 file	Create
New pyproject.toml	1 file	Create
Delete TS/Node files	4-5 files	Delete

Risks and Considerations

1. wait_for_result() polling pattern: API steps poll state in a while True loop with asyncio.sleep(1). This should still work with new Motia, but needs verification on whether the new state API still wraps values in a data field (old Motia state.get() returns {"data": actual_value}). If the wrapping is removed, the result["data"] unpacking logic in wait_for_result() needs adjustment.

2. sys.path hacks: Event steps manually add utils_path to sys.path. The new Python runtime's directory handling may affect this — needs testing.

3. iii engine system dependency: The new architecture requires the iii Rust engine. This needs to be incorporated into the Nix flake.

4. State parameter semantics: context.state.set(trace_id, key, value) maps to ctx.state.set(group, id, value) — parameter positions are identical, semantics map 1:1 (trace_id → group, key → id). Low risk.

[shirohasuki]

Finally, completed in #2 and #6