Commit d064bdf

- 2026-10-04 [`ses_ef81ca107ffet5DwnFLaGWlUap`](../sessions/2026-10-04-scroll-anchor.md) -

unchanged; it does not interact with the scrolled-up drift, which comes

from the 100-message prune. Evidence: the installed

`1.18.34-vt-61-907b3bc518` held a scrolled-up view through a streamed

agent run, the same as vanilla `dev`.

- Status: active

- Integration branch: `dev-nowaker`

- Development branch(es): `fix-scroll-follow` (off upstream `dev` `907b3bc518`; also the upstream PR head)

- First local commit: `6ff168d896`

- Current local commit(s): `6ff168d896`

- Upstream base when introduced: `907b3bc518` (upstream `dev`, contains `v1.18.34`)

- Last checked against upstream: `907b3bc518` (upstream `dev`)

- Upstream: existing issue [#41243](https://github.com/anomalyco/opencode/issues/41243)

(root cause of #29094 / #4196), PR [#53219](https://github.com/anomalyco/opencode/pull/53219)

Relayed by coordinator `ses_ef8235798ffejGr4sa22eXmVNv`, quoting the user:

- While scrolled up, new and streaming AI output does not move the viewport.

- At the bottom, the transcript keeps following the stream; `End` and

scrolling back down resume following.

- Scrolling on prompt submit is

[Keep the scroll position when a prompt is submitted](./2026-10-04-keep-scroll-on-submit.md).

- No setting: this is a bug fix.

- Sticky scroll is not the cause. In sessions under 100 messages, wheel,

PageUp and line-up already hold on vanilla `dev`, both while streaming and

through tool calls.

- The cause is `context/sync.tsx`, which keeps at most 100 messages per

session and `shift()`s the oldest on every new one. Each drop removes rows

above the viewport under a fixed `scrollTop`, so the text slides up until it

reaches the bottom, where sticky scroll re-engages.

- The fix measures the layout change instead of predicting the pruned height

(the approach of upstream PR #41247, auto-closed without review). It needs no

`id` on assistant message boxes, and it covers any height change above the

viewport.

- The root renderable emits `layout-changed` after computing the layout and

before any renderable reads it. `ScrollBox` content's own `resize` fires too

late in the frame: the test showed the drift with that hook.

- The TUI streaming render throttle does not interact: it only lowers how often

frames, and so this check, run.

| Commit | Workday | Change | Stable seam |

|---|---|---|---|

| `6ff168d896` | 2026-10-04 | Re-anchor the first visible transcript child after every layout while not at the bottom | `keepScrollAnchor()` in `packages/tui/src/util/scroll.ts`; its call in the session `<scrollbox ref>` in `packages/tui/src/routes/session/index.tsx`; `packages/tui/test/util/scroll.test.tsx` |

- `bun test test/util/scroll.test.tsx` in `packages/tui`: 2 pass. With the

hook disabled, the anchor test fails (`item 25` expected, `item 28`

received).

- `bun test` in `packages/tui` on `dev-nowaker` + the fix: 219 pass, 1 skip,

0 fail; `bun typecheck` passes.

- Manual surface (isolated XDG dirs, tmux socket `oc-tui-scroll`, local fake

OpenAI-compatible server streaming markdown, reasoning and a bash tool call

per step, session past 100 messages): on vanilla `dev` the scrolled-up view

slid from `Step 96` to `Step 101` in 20 s. With the fix it stayed at

`Step 586 closing` / `Step 587 bullet two` for 40 s, and `End` resumed

following at `Step 596`.

- 2026-10-04

[`ses_ef81ca107ffet5DwnFLaGWlUap`](../sessions/2026-10-04-scroll-anchor.md)

- `6ff168d896`: introduce; upstream PR #53219 closing #41243; build and

install on desktop and m4max.

- Drop the fork commit once PR #53219 (or an equivalent fix for #41243) is in

upstream `dev`.

- If upstream removes or changes the 100-message prune in `context/sync.tsx`,

keep the anchor anyway: it covers any height change above the viewport.

- The session transcript `<scrollbox>` ref still calls

`keepScrollAnchor(renderer, r)`.

- `@opentui/core` still emits `layout-changed` from `RootRenderable` after

`calculateLayout()` and before `updateLayout()`. Run

`test/util/scroll.test.tsx` after every opentui bump.

- Workday: 2026-10-04

- Session: `ses_ef81ca107ffet5DwnFLaGWlUap`

- Agent/platform: `Sisyphus - ultraworker` on `anthropic/claude-opus-5-5` (variant high) / linux, Vibeterm

- Repository: `~/projekty/webapps/opencode`

- Integration branch: `dev-nowaker`

- Development branch(es): `fix-scroll-follow` (worktree under `.vibeterm/worktrees/`, off upstream `dev` `907b3bc518`)

- Upstream base: `907b3bc518` (upstream `dev`, contains `v1.18.34`); unchanged

- Source result commit(s): `6ff168d896` (cherry-pick of `ecfa7cb318` on `fix-scroll-follow`)

- Forklog commit: this file's introducing commit

Spawned by coordinator `ses_ef8235798ffejGr4sa22eXmVNv` (item 1 of "opencode

TUI improvements"), quoting the user:

- Reproduce on vanilla `dev`, fix it, open an upstream PR, land on

`dev-nowaker`, and build both hosts.

- Submit-time scrolling is item 2, another session.

- No TUI tab, vibeterm tmux server or `opencode-serve-*` unit restarted.

| Repository | Branch | Before | After | Action |

|---|---|---|---|---|

| `opencode` (GitHub fork + GitLab) | `fix-scroll-follow` | - | `ecfa7cb318` | new branch off upstream `dev` `907b3bc518`; head of PR #53219 |

| `opencode` | `dev-nowaker` | `0b0357e848` | `6ff168d896` | cherry-pick, fast-forward; pushed to `origin` and `nowaker-github` |

| `opencode` (m4max) | `dev-nowaker` | `0b0357e848` | `6ff168d896` | fast-forward from `origin` |

| Feature | Outcome | Evidence |

|---|---|---|

| [Keep a scrolled-up reader's place in a long session](../features/2026-10-04-scroll-anchor.md) | introduced | regression test fails without the fix; isolated TUI before/after samples |

| [TUI streaming render throttle](../features/2026-08-25-tui-stream-throttle.md) | re-verified, unchanged | installed fork binary held a scrolled-up view through a streamed agent run under 100 messages, same as vanilla |

- No new upstream issue. Searching for "scroll jumps while streaming",

"scrolled up auto scroll", "scroll position long session",

"auto-scroll interrupts reading" and "sticky scroll" found open issue

#41243. It records the same root cause; its PR #41247 was closed by

`automated-pr-cleanup` on 2026-09-08 without review. PR #53219 closes

#41243.

- Vanilla `dev` from source, TUI in tmux socket `oc-tui-scroll`, isolated XDG

dirs, local fake OpenAI-compatible servers in the worktree's `tmp/`:

- under 100 messages, plain text, then a multi-step agent run with

reasoning and bash tool calls: wheel, PageUp and line-up hold for 8-20 s

while the stream continues; `End` shows the stream moved on;

- a session past 100 messages, token-sized markdown: the scrolled-up view

slides from `Step 96` to `Step 101` in 20 s;

- instrumented run: `scrollTop` and the manual-scroll flag stay fixed while

the first child's offset jumps by its height on every prune.

- Fix from source, same session past 100 messages: view stays at

`Step 586 closing` / `Step 587 bullet two` for 40 s; `End` resumes

following at `Step 596`.

- `packages/tui`: `bun test test/util/scroll.test.tsx` 2 pass (anchor test

fails with the hook disabled); full `bun test` on `dev-nowaker` + fix:

219 pass, 1 skip, 0 fail; `bun typecheck` passes. On upstream `dev` the full

suite had one failure in `DiffViewerFileTree`, which passed twice alone.

- Build command: `.vibeterm/build.sh` in each host's primary checkout.

- Installed artifact: desktop and m4max both `1.18.34-vt-78-907b3bc518`,

built at `6ff168d896`; desktop inode `49955453`. Both binaries contain the

`layout-changed` anchor and the retry-header marker.

- Running services: none restarted on either host; running TUIs pick up the

build only after their own restart.

- `6ff168d896` - fix and regression test.

- Required trailer: `AI-Session-ID: ses_ef81ca107ffet5DwnFLaGWlUap`

- The installed binaries were not driven in a session past 100 messages; the

source build was.