Real web client, Chromium 1280×800, light theme; independent fresh databases and identical synthetic fixtures on both commits. The replay agent negotiates each specified protocol version, sends real session/update notifications, and the real ACP adapter/server persists and renders them.
Steps: seed an old-name tool with title, read kind, in_progress status, OLD OUTPUT, rawInput {path:'/workspace/old.txt',obsolete:true}, and _meta {old:true}; then independently clear all seven fields, replace rawInput with {path:'/workspace/new.txt'}, or omit fields. Open each thread, expand the work group and available tool details, wait for loading to finish, and capture that case separately.
Supplemental cases make otherwise hidden state visible: generic kind 'other' exposes replacement/input keys and the title; MCP identity metadata makes _meta clearing visible; a failed initial status makes status clearing visible through the failure icon. Synthetic /workspace paths avoid exposing internal directories. The empty all-clear Tool row has no disclosure control; input-only/output-only cases retain details and are expanded on both sides.
Observed: base retains obsolete:true and nulled values; head drops the obsolete key and clears the visible fields. Omitted fields retain their old input/output on both sides. Both v2 and v1 show this change; the v1 run documents changed behavior, not preservation of the base's v1 behavior. The arbitrary name field has no visible representation, so its clearing and the v1 null-name exception remain visually unverified.
## Negotiated ACP v2
### Scenario: ACP tool updates clear explicit nulls and replace input
**Proven: the scenario fails on base [2755a951a1](https://github.com/pingdotgg/t3code/commit/2755a951a18b7b1725cf165718d014c3b7261245) and passes on head [aa3c4c3b7f](https://github.com/pingdotgg/t3code/commit/aa3c4c3b7f524161e5654b8f86268cfb05439c8f).**
| | Before [2755a951a1](https://github.com/pingdotgg/t3code/commit/2755a951a18b7b1725cf165718d014c3b7261245) | After [aa3c4c3b7f](https://github.com/pingdotgg/t3code/commit/aa3c4c3b7f524161e5654b8f86268cfb05439c8f) |
| --- | --- | --- |
| Result | ❌ failed
ASSERTION_FAILED: expected "AgentAgentApply replacement-visible updateWorked for 839ms3:41 AMOriginal title3:41 AMpath /workspace/new.txtobsolete true[\n {\n \"type\": \"content\",\n \"content\": {\n \"type\": \"text\",\n \"text\": \"OLD OUTPUT\"\n }\n }\n]T3 Codereplacement-visible update applied.3:41 AM" not to contain "obsolete" | ✅ passed |
| protocol 2 input visible |  |  |
| protocol 2 replacement visible |  |  |
| protocol 2 title visible |  |  |
| protocol 2 replacement |  |  |
| protocol 2 clear |  |  |
| protocol 2 omitted |  |  |
| protocol 2 input |  |  |
| protocol 2 content |  |  |
| protocol 2 title |  |  |
| protocol 2 kind |  |  |
| protocol 2 name |  |  |
| protocol 2 meta |  |  |
| protocol 2 status |  |  |
| failure |  | |
[v2 base complete recording](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/8745ff0e0b8c1626/video.webm) | [v2 head complete recording](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/03389f397ced3bd2/video.webm)
## Negotiated ACP v1
### Scenario: ACP tool updates clear explicit nulls and replace input
**Proven: the scenario fails on base [2755a951a1](https://github.com/pingdotgg/t3code/commit/2755a951a18b7b1725cf165718d014c3b7261245) and passes on head [aa3c4c3b7f](https://github.com/pingdotgg/t3code/commit/aa3c4c3b7f524161e5654b8f86268cfb05439c8f).**
| | Before [2755a951a1](https://github.com/pingdotgg/t3code/commit/2755a951a18b7b1725cf165718d014c3b7261245) | After [aa3c4c3b7f](https://github.com/pingdotgg/t3code/commit/aa3c4c3b7f524161e5654b8f86268cfb05439c8f) |
| --- | --- | --- |
| Result | ❌ failed
ASSERTION_FAILED: expected "AgentAgentApply replacement-visible updateWorked for 624ms3:44 AMOriginal title3:44 AMpath /workspace/new.txtobsolete true[\n {\n \"type\": \"content\",\n \"content\": {\n \"type\": \"text\",\n \"text\": \"OLD OUTPUT\"\n }\n }\n]T3 Codereplacement-visible update applied.3:44 AM" not to contain "obsolete" | ✅ passed |
| protocol 1 input visible |  |  |
| protocol 1 replacement visible |  |  |
| protocol 1 title visible |  |  |
| protocol 1 replacement |  |  |
| protocol 1 clear |  |  |
| protocol 1 omitted |  |  |
| protocol 1 input |  |  |
| protocol 1 content |  |  |
| protocol 1 title |  |  |
| protocol 1 kind |  |  |
| protocol 1 name |  |  |
| protocol 1 meta |  |  |
| protocol 1 status |  |  |
| failure |  | |
[v1 base complete recording](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/0eccfd266374e58d/video.webm) | [v1 head complete recording](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/5bb97d22542b7e68/video.webm)
[Scenario](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/9d64edcbbc7760a4/acp-cleared-fields.e2e.ts) · [Replay driver, fixtures and harness patch](https://gh-file-drop-api-prod-mi5fy3sowv63ufte.pinglabs.workers.dev/f/5db4df6ff7eab1de/acp-proof-driver.zip)