## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - Agents make progress in heartbeats: the server wakes an agent
session, it does a slice of work on an issue, records a disposition, and
exits
> - Benchmarking identical coding tasks run as Paperclip-orchestrated
agent pairs vs invoking the same agent harness directly measured a
1.8–2.2× wall-clock slowdown for the Paperclip pairs, dominated by
per-heartbeat orchestration overhead rather than model time
> - Two contributors stood out: (1) since PF-4 (#4838) every
`heartbeat_timer` wake starts a brand-new task session, so continuation
work on a specific issue repays the full session-start and
re-orientation cost on every heartbeat; (2) in degraded environments
agents burn many tool calls retrying the same failing control-plane
write before giving up
> - This pull request reuses the task session for issue-scoped timer
wakes (keeping the PF-4 fresh-session rule only for unscoped exploratory
wakes, which were the original context-bloat case) and adds a
bounded-retry rule to the wake prompt and core skill: after 2
consecutive failures of the same control-plane write, stop retrying it
for the rest of the heartbeat and rely on the adapter/runtime status
channel
> - The benefit is materially less wall-clock and token overhead per
heartbeat while preserving the context-bloat protection PF-4 was added
for
## Linked Issues or Issue Description
Refs #4838 (merged PF-4 change whose reset rule this refines), Refs
#5287, Refs #1907 (related timer-heartbeat session work).
No public GitHub issue exists for the slowdown itself; bug-report
fields:
- **What happened:** Agent pairs orchestrated through Paperclip
heartbeats complete identical task sets 1.8–2.2× slower (wall-clock)
than the same harness invoked directly. Profiling attributed the gap to
per-heartbeat orchestration overhead: every timer wake discards the task
session (full session start + re-orientation), and in degraded
environments agents repeatedly retry the same failing control-plane
write.
- **Expected behavior:** Heartbeat orchestration should add minimal
wall-clock overhead on top of the underlying harness; issue-scoped
continuation work should not pay a fresh-session tax each interval.
- **Steps to reproduce:** Run a fixed benchmark task set once through
Paperclip issue heartbeats and once via direct harness invocation with
the same model/config; compare wall-clock totals.
- **Version/commit:** master @ 3d23c3b2c3, self-hosted deployment.
## What Changed
- `server/src/services/heartbeat.ts`: `shouldResetTaskSessionForWake`
now resets only for `heartbeat_timer` wakes with no derivable task key
(unscoped exploratory wakes). Issue-scoped timer wakes reuse the issue's
task session. `describeSessionResetReason` updated to stay in exact
agreement.
- `server/src/__tests__/heartbeat-timer-wake-session-reset-pf4.test.ts`:
new cases for scoped vs unscoped timer wakes, plus the scoped case added
to the reset/reason agreement invariant.
- `packages/adapter-utils/src/server-utils.ts`: wake prompt template and
execution contract gain a bounded-retry rule — after 2 consecutive
failures of the same control-plane write, stop retrying it for the rest
of the heartbeat, continue useful work, report the failure in the final
response, and use the adapter/runtime status channel as the sanctioned
fallback.
- `packages/adapter-utils/src/server-utils.test.ts`: asserts the new
prompt lines are present in both the template and the rendered wake
prompt.
- `skills/paperclip/SKILL.md`: documents the same bounded write-retry
rule in the core Paperclip skill.
## Verification
- `node_modules/.bin/vitest run
packages/adapter-utils/src/server-utils.test.ts` — 1 file, 83 tests
passed
- `cd server && node_modules/.bin/vitest run
src/__tests__/heartbeat-timer-wake-session-reset-pf4.test.ts` — 1 file,
14 tests passed
- Both run on this branch rebased onto current master (3d23c3b2c3)
## Risks
- Behavioral shift: issue-scoped timer wakes now reuse sessions, so a
long-lived issue session can grow across heartbeats. Mitigated by
keeping the PF-4 reset for unscoped wakes (the originally observed bloat
case) and by existing session compaction.
- Prompt/skill text changes alter agent guidance; the new rule is scoped
narrowly to repeated failures of the same control-plane write.
- No migrations, no API or schema changes, no dependency changes.
## Model Used
- Claude (Anthropic) — `claude-fable-5` (Fable 5), extended reasoning
with tool use, driven via Claude Code / Claude Agent SDK.
## 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
- [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>
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