Files
PaperClipAI/tests
DottaandPaperclip 6dcf4160dd perf(chat): load recent messages and page history on scroll (#18358)
## Thinking Path

> - Paperclip lets people manage work done by agents.
> - A standing agent chat can hold months of conversation.
> - The chat route forced full-history mode, bypassing compact task
loading.
> - A cold visit fetched lifetime run summaries and hydrated historical
transcripts.
> - This PR starts with 20 recent messages and loads earlier pages on
upward scroll.
> - It preserves the reader's position, current questions, and draft
while history grows.

## Linked Issues or Issue Description

**What happened?**

Standing agent chats forced full-history loading. A long conversation
fetched full activity and run history before it became readable. Earlier
comments also used an explicit load control.

**Expected behavior**

Open a small recent conversation quickly. Load older messages when the
reader scrolls upward. Show an inline loading state. Keep the visible
message and composer mounted through paging, live updates, and Back
navigation.

**Steps to reproduce**

1. Open a standing agent chat with hundreds of messages and completed
runs.
2. Use a fresh browser query cache.
3. Observe full activity and run reads plus transcript requests for
historical runs.
4. Compare the recent window and upward paging after this change.

Related work: #18312 and #18323 restored compact task and collection
loading. #14848 added reopening of visited agent chats. A GitHub search
found no open PR for this chat-history optimization.

## What Changed

- Return 20 contiguous recent comments for standing chats, with a stable
oldest cursor. Keep the existing compact task exchange contract. Use the
existing company/issue/time index for cursor reads.
- Keep chats compact even if their task view previously expanded
history. Retain observed messages through live catch-up and cache-backed
return visits.
- Keep fetched history pages, acknowledged sends, and the observed
recent cursor separate. Reconcile live replies without losing history
after a send or deleted cursor.
- Hydrate metadata only for newly revealed message/run IDs; preserve
prior batches while paging. Slow-send recovery refreshes the recent
window. Receipts failures have an independent retry.
- Hydrate run summaries only for loaded messages and the latest turn.
Validate batches of at most 100 run IDs and keep the existing
issue/company access rules.
- Reuse hydrated terminal native streams when only history membership
changes. Preserve retry, resume, mode changes, reconnect recovery, and
interrupted recovery reads.
- Load older messages, decision receipts, and task handoffs through
upward scrolling. Support wheel, touch, and keyboard input. Keep pending
questions visible.
- Reserve a status slot while loading. Preserve a logical message anchor
and the mounted composer. Pause failed page reads until an inline Retry.
- Add database, route, controller, and scroll regressions, plus an
opt-in production-build browser rig for long chats on desktop and
mobile. Update design and feature/access documentation.

## Verification

- The real PostgreSQL cold-open suite passes all 12 tests, including
contiguous pages with equal timestamps, complete history, company
denial, and scoped run IDs.
- Activity route and OpenAPI suites pass 53 tests. The route run allowed
local cold-import overhead; CI retains the repository's normal timeouts.
- Three new paging regressions fail against the unchanged source. The
candidate's focused paging/window suite passes 26 tests. Broader UI
verification is recorded below when complete.
- Desktop and mobile browser acceptance covers recent-only startup,
per-frame reveal geometry, delayed and failed older pages, stable
reading anchors and drafts, Back, older comment links, and one persisted
live reply.
- Full workspace typecheck and build passed locally. The final UI source
also passes its typecheck and production build.
- Affected UI suites pass: 212 controller/history/paging tests, 352
thread/scroller tests, 26 native-stream tests, plus metadata batching
and live-cache hydration coverage. The issue mutation/access route suite
passes 179 tests.
- All 22 final desktop/mobile browser journeys pass, including delayed
image growth. The isolated second-page request proof also passes six
repeated desktop/mobile runs. A separate 6,000-message, 3,000-run
fixture passes cold-open and delayed-paging checks on both screen sizes,
still opening 20 messages and loading one 50-message page.
- Final matched production timings use baseline `aa58fa1073`
(`index-BaRiMbxd.js`) and candidate UI source `f9a26b9783`
(`index-DPWTbsFF.js`, identical application source at final head
`bf71ffd5af`). Chromium 151.0.7922.34, 1440×900, 4× CPU throttle, no
added network latency, browser HTTP cache disabled, fresh application
cache for each cold visit. Both variants block service workers and use
the same warm local API server and immutable 600-message/300-run
fixture. Only document HTML is intercepted for both variants; API
requests are real. The common API revision is `109981f8c1`; subsequent
commits change only UI and tests.

| Usable conversation | Baseline median (range) | Candidate median
(range) |
| --- | --- | --- |
| Cold direct URL | 6.57 s (5.69–7.45) | 3.07 s (2.50–3.28) |
| Warm in-app return | 3.76 s (3.54–4.76) | 0.67 s (0.58–1.46) |
| Back return | 2.53 s (2.12–4.20) | 0.51 s (0.47–1.18) |

Five pairs alternate order. Every paired difference favors the candidate
for all three journeys. Readiness requires a revealed, fully visible
latest reply above the composer and an editable composer. Return timing
starts after the Tasks route renders. Cold API requests fall from
953–954 to 71; API wire bytes fall from 517–559 KB to about 49 KB.
Separate CPU profiles and request waterfalls confirm the removal of
lifetime event hydration and are excluded from the five timing pairs.
Both variants have the same expected missing optional plan document
(404) and no browser exceptions. Control recent-window API reads have
medians of 37 ms / 32 ms, with shared-host outliers up to 376 ms.

The 6,000-message recent-window SQL uses
`issue_comments_company_issue_created_at_idx` (22 index rows read for a
21-row probe). Geometry assertions retain a 2-pixel tolerance for the
reading anchor and first-reveal layout. These are local synthetic
measurements, not deployed staging latency. Earlier timing probes are
excluded because they did not isolate service workers or composer
clearance. Final head `bf71ffd5afb5684ba9105a3127f617e7adf5139c` has 55
successful checks, three optional skips and one neutral result, with no
failures or pending checks. Greptile is 5/5 with no open review
findings.

### Failure record

Early local attempts exposed an unconditional scroller wrapper that
changed the old task layout, and automatic retries on chat page
failures. Both were corrected. The original task scroller structure
stays in place. Metadata request assertions wait for initial connection
recovery to settle, then verify only the new page’s reads;
retry/resume/reconnect revalidation remains intentional.

The initial review caught a send-before-scroll cache defect; its
controller regression failed before the fix. Later rapid-paging checks
caught scroll readiness being gated by metadata after the first reveal;
readiness now stays enabled once revealed. Live replies use the separate
acknowledged-message cache, then catch up from the server cursor.

Visual review exposed a pagination wrapper bypassing existing composer
clearance. The body is again a direct scroller child; cold-open browser
checks require the full latest reply above the composer. A
resize-observer regression failed before the fix and now passes.
Controlled delayed inline images prove both pinned following and a
stable reading anchor on desktop/mobile.

The first performance fixture lacked valid native event envelopes and
caused missing-log fallbacks. It is excluded from latency claims. The
final fixture uses saved native assistant events and conversation
session generations. The live test uses a temporary fixture-agent key,
attributes the reply to an existing synthetic run, and revokes the key.
It starts no model or agent process.

Local database attempts failed during a Docker shutdown. The retained
disposable database was restored and its suite passed. Early fixture
errors included a missing conversation identity field and session
generation. Mobile test setup also selected an offscreen sidebar link
and reused queued human input. Optional announcements could intercept
input; the fixture now dismisses them before the journeys. The scroll
observer now waits for the delivered wheel event and settled animation
frames, including when the viewport is already at the top. A
concurrently running live test briefly changed another probe’s row
count; the final acceptance and timing runs were sequential on separate
fixtures. The final rig uses the visible mobile navigation and a saved
agent reply. Anchor observation waits for the user's scroll to settle
before measuring the effect of live updates.

The full local `pnpm test:run` attempt hit repeated embedded PostgreSQL
initialization failures and failures in untouched native-session
executor suites; it was stopped after the repeated environment failures.
The targeted real-PostgreSQL suite passed, and final-head CI is required
before handoff. The first CI run also caught an exact mock expectation
missing the added company scope; the expectation is updated and its
179-test suite passes. The final-head first CI attempt also stalled an
assigned child task in the existing plan-approval scenario, then hit a
heartbeat-run row lock timeout during fixture cleanup. The failed shard
and aggregate check passed on an unchanged rerun of the same commit.
Scenario assertions and timeouts were unchanged. The failure and rerun
are retained in [CI run
41116120430](https://github.com/paperclipai/paperclip/actions/runs/41116120430).

## Risks

- Historical transcript diagnostics no longer load on a cold chat open.
Saved messages and conversation events remain available; diagnostic run
views keep their full records.
- Cursor paging must not omit comments with equal timestamps. Database
tests cover timestamp/UUID ordering and the complete set.
- Prepended or late content can move the reader. Browser checks cover
retained row identity, viewport offsets, mounted drafts, and Back.
Previously loaded pages stay in the query cache for its existing
lifetime.
- Local synthetic evidence does not establish deployed staging latency.
This PR does not merge or deploy the change.

## Model Used

OpenAI Codex, GPT-6 family, with reasoning, tool use, and code
execution. The exact backend deployment ID and context window were not
exposed in this session.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass (affected checks; limits
are recorded above)
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>
2026-10-30 15:12:24 -05:00
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