# Phase 153 Summary

Status: implemented in working tree

## Goal

Close the next post-`v1.78` gap by turning route-transition eligibility into an
operator-visible gate surface instead of leaving blocked versus available
yielding implicit across route-choice and checkpoint artifacts.

## What Landed

- route transition-gate payload construction and runtime/read-path rendering in:
  - `research/knowledge-hub/knowledge_hub/runtime_read_path_support.py`
- runtime protocol and research-question rendering for the new transition-gate
  section in:
  - `research/knowledge-hub/knowledge_hub/kernel_markdown_renderers.py`
  - `research/knowledge-hub/knowledge_hub/runtime_bundle_support.py`
- replay support for blocked versus available versus checkpoint-required route
  transition visibility in:
  - `research/knowledge-hub/knowledge_hub/topic_replay.py`
- public runtime-bundle schema coverage for `route_transition_gate` in:
  - `research/knowledge-hub/runtime/schemas/progressive-disclosure-runtime-bundle.schema.json`
- one new isolated acceptance lane:
  - `research/knowledge-hub/runtime/scripts/run_hypothesis_route_transition_gate_acceptance.py`
- new contract/runtime coverage in:
  - `research/knowledge-hub/tests/test_hypothesis_route_transition_gate_contracts.py`
  - `research/knowledge-hub/tests/test_runtime_scripts.py`
  - `research/knowledge-hub/tests/test_topic_replay.py`
  - `research/knowledge-hub/tests/test_schema_contracts.py`
- documentation and runbook updates across:
  - `research/knowledge-hub/README.md`
  - `research/knowledge-hub/runtime/README.md`
  - `research/knowledge-hub/runtime/AITP_TEST_RUNBOOK.md`

## Outcome

Phase `153` now closes the first bounded route transition-gate slice:

- `status --json`, `research_question.contract.md`, and the runtime protocol
  note now surface one `route_transition_gate` summary with `blocked`,
  `available`, and `checkpoint_required` states
- `replay-topic --json` exposes the same transition-gate payload plus the
  route-transition-gate status on both current-position and conclusions lanes
- the new isolated acceptance proves AITP can distinguish blocked,
  directly-available, and operator-checkpoint-gated yielding without automatic
  route mutation
