---
docType: review
layer: project
reviewType: slice
slice: pipeline-executor-and-loops
project: squadron
verdict: PASS
sourceDocument: project-documents/user/slices/149-slice.pipeline-executor-and-loops.md
aiModel: z-ai/glm-5
status: complete
dateCreated: 20260403
dateUpdated: 20260403
---

# Review: slice — slice 149

**Verdict:** PASS
**Model:** z-ai/glm-5

## Findings

### [PASS] Core Abstractions Align with Architecture

The executor design correctly consumes `PipelineDefinition` from the loader, uses step type registry for expansion, and delegates to action implementations via the registry pattern. This matches the component architecture diagram showing "Definition Loader & Validator → Step Sequencer → Step Type Registry → Action Registry."

### [PASS] Scope Boundaries Properly Enforced

The slice correctly implements 140 scope items (executor, basic loops, collection loops, convergence stub) while deferring 150 items (state persistence), 151 items (CLI integration), and 160 items (convergence strategies, conversation persistence). The exclusion list is explicit and accurate.

### [PASS] Convergence Loop Stub Follows Architecture

The architecture specifies: "In 140, a step with `loop.strategy` is treated as a basic loop with `max` iterations — the strategy field is acknowledged but the convergence logic is no-op stub." The slice correctly implements this by logging a warning and falling back to basic max-iteration behavior.

### [PASS] Each Step Type Special Handling is Appropriate

The architecture's component diagram shows `each` in the Step Type Registry, but the slice correctly identifies that `each` needs executor-level handling due to nested step recursion. This is a legitimate implementation detail that doesn't violate the architecture — step types still expand, just via a different mechanism for this special case.

### [PASS] Closed Loop Condition Grammar is Defensible

The architecture states: "[DEFERRED → 149] The condition grammar (`until: review.pass`) is illustrative syntax. The formal definition — whether conditions are field paths into `ActionResult`, named properties, or a structured expression — is a 149 design decision." The slice's decision to implement a closed enum of three conditions rather than a general expression parser is architecturally sound. The rationale explicitly addresses the architecture's risk of "Reinventing LangGraph" by keeping the vocabulary constrained.

### [PASS] Item Binding Mechanism Follows Architecture Guidance

The architecture's open question #5 states collection loop item binding semantics are a 149 design decision. The slice's approach — dot-path traversal into nested params dict — is the "as simple as possible" approach the architecture suggested.

### [PASS] Dependency Directions Correct

The executor correctly depends on abstractions from prior slices: `get_step_type()` from 147, `get_action()` from actions, `ModelResolver` from 142, `PipelineDefinition` from 148, and `ContextForgeClient` from 126. No hidden dependencies or layer violations detected.

### [PASS] Integration Points Match Architecture Expectations

The slice correctly provides `on_step_complete` callback for state manager integration (slice 150), `start_from` parameter for resume, and `PipelineResult`/`StepResult` types for CLI consumption. The architecture's state file schema aligns with what the executor produces.

### [PASS] Result Types in Executor Scope

The slice places `StepResult`, `PipelineResult`, and `ExecutionStatus` in `executor.py` rather than `models.py`. This is appropriate — they are executor output types, not pipeline model inputs. The architecture does not mandate a specific file location for these.

### [PASS] Async Design Consistent with Architecture

The architecture notes "Subprocess calls run via `asyncio.to_thread` to avoid blocking the async executor." The slice correctly makes the executor and all actions async, enabling I/O-bound operations to run without blocking.
