feat: inject periodic mid-loop reminder every 5 turns to counter instruction drift

[zjshen14]

Summary

• Adds buildPeriodicReminder(turn) to src/core/prompt.ts that returns a compact [reminder: ...] block every PERIODIC_REMINDER_INTERVAL (5) turns, and empty string otherwise
• Wires it into applyReminderToLastResult in src/core/agent.ts alongside the existing event-driven reminders
• Adds 3 unit tests in prompt.test.ts and 3 integration tests in agent.test.ts covering: fires at multiples of the interval, silent before the interval, fires again at the second multiple

Related issue

Part of #19 — item 5: "Mid-loop system-reminder injection"

Why

Event-driven reminders (AGENT_REMINDERS) fire at most once per run and only when specific tools are called (writes, git). In long sessions the model drifts from git rules, edit discipline, and testing requirements. A periodic reminder re-anchors it cheaply (~10 tokens every 5 turns) without disrupting short sessions where the interval is never reached.

Test plan

• npm run typecheck && npm run lint && npm run format:check && npm test — all pass (654 tests, 0 failures)
• New buildPeriodicReminder unit tests: fires at turn 5, 10; silent at turns 1–4; silent at turn 0
• Agent integration tests: reminder appears in the tool_result event at exactly turn 5 and turn 10; absent before

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[zjshen14]

Review: feat: inject periodic mid-loop reminder every 5 turns

What's good: The implementation is clean and well-contained. buildPeriodicReminder is a pure function, correctly placed in prompt.ts, and wired into the existing applyReminderToLastResult path with minimal structural disruption. Tests are thorough: unit tests cover turns 0, 1–4, 5, and 10; integration tests verify the tool_result event carries the reminder at exactly the right turns and not before. Exporting PERIODIC_REMINDER_INTERVAL so tests don't hardcode 5 is the right call. CI is green, no conflicts.

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Concerns

1. Wording diverges from AGENT_REMINDERS, creating overlapping-but-inconsistent instructions

PERIODIC_REMINDER_TEXT paraphrases the event-driven reminders rather than reusing their exact text:

AGENT_REMINDERS	PERIODIC_REMINDER_TEXT
"never commit or push without an explicit user request"	"commit only when explicitly asked"
"verify the change works — find and run the project's test command before reporting done"	"run tests after changes"

On any turn where a write call first occurs and it's a multiple-of-5 (e.g. the very first write happens at turn 5), both sets fire in the same tool result and the model receives two slightly different phrasings of the same rule back-to-back. Using the exact text from AGENT_REMINDERS, or deriving PERIODIC_REMINDER_TEXT from that array, would keep the two reminder channels consistent and avoid the potential for the model to treat them as distinct constraints.

2. No opt-out path for custom system prompts

Operators overriding the default instructions via OPENCLI_SYSTEM_MD have no way to suppress or reconfigure the periodic reminder — it fires unconditionally regardless of what the custom prompt says. If the custom prompt already has its own reminder cadence, or deliberately omits certain rules, the hardcoded PERIODIC_REMINDER_TEXT will contradict or duplicate it silently. A PERIODIC_REMINDER_INTERVAL=0 env var (alongside the existing OPENCLI_* family) or a nullable export would make this composable without adding complexity to the hot path.

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Recommendation

Merge after addressing concern #1 (wording consistency) or adding a comment explaining why the divergent phrasing is intentional. Concern #2 is lower priority — acceptable to track as a follow-up if the feature ships first.

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[zjshen14]

Rebased onto current main (commit 706dceb) to resolve merge conflicts. The rebase was non-trivial: since PR #211 was created, the agentic loop in agent.ts was refactored — the applyReminderToLastResult private method was removed and its logic was inlined back into run(). The conflict resolution:

• Applied the PR's intended change to the inline reminder code (renamed reminder → eventReminder, added periodicReminder = buildPeriodicReminder(turns), combined them)
• Kept HEAD's monolithic run() structure unchanged (did not re-introduce the extracted private methods, which were from the PR's old base)
• Kept both test suites that were added at the same location (Agent activate_skill — conversation well-formedness from HEAD + Agent periodic reminder injection from this PR)

All 716 tests pass (6 new from this PR). Branch is now conflict-free and ready for review.

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[zjshen14]

Re-review: feat: inject periodic mid-loop reminder every 5 turns (post-rebase, SHA cf92fdc)

This is a re-review following the rebase onto main @ 706dceb. CI is all green (Typecheck+Lint+Test, CodeQL, Analyze) and mergeable_state is clean.

Rebase adaptation

The rebase correctly handles the applyReminderToLastResult refactor that landed on main between the original PR and today: the extracted private method was re-inlined, and the PR's periodicReminder is now combined with eventReminder before the single if (combined && results.length > 0) guard. The logic is equivalent to the original intent and there are no mechanical issues.

buildPeriodicReminder(turns) is called after turns++, so it fires at turns 5, 10, 15, … as the tests verify. No change there.

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Prior concerns — still unaddressed

Both concerns from the June 4 review remain open in this rebased state:

1. Wording diverges from AGENT_REMINDERS (prompt.ts:73–82)

AGENT_REMINDERS says:

• "never commit or push without an explicit user request"
• "verify the change works — find and run the project's test command before reporting done"

PERIODIC_REMINDER_TEXT says:

• "commit only when explicitly asked" — omits "or push"; weaker phrasing
• "run tests after changes" — significantly vaguer than the event-driven version
• "prefer targeted edits over full rewrites" — new constraint not present in AGENT_REMINDERS at all

The two channels now teach the model three slightly different versions of the same rules. Deriving PERIODIC_REMINDER_TEXT from AGENT_REMINDERS (e.g. AGENT_REMINDERS.map(r => r.text).join('; ')) would keep them in sync mechanically and guarantee they can't diverge again. Alternatively, a short comment explaining why the shorter/different phrasing is intentional (e.g. "compact form for token budget") resolves the concern without a code change.

2. No opt-out path for OPENCLI_SYSTEM_MD overrides

Operators using a custom system prompt via OPENCLI_SYSTEM_MD have no way to suppress or reconfigure the periodic reminder. Still lower priority — still acceptable as a follow-up.

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Recommendation

Merge after addressing concern #1 — either align the PERIODIC_REMINDER_TEXT wording with AGENT_REMINDERS, or add a brief inline comment explaining why the intentional divergence is correct. Concern #2 remains a follow-up item.

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[zjshen14]

Addressed concern #1 from the re-review (commit 35f9e7c).

What changed:

• PERIODIC_REMINDER_TEXT is now derived from AGENT_REMINDERS via AGENT_REMINDERS.map((r) => r.text).join("; ") instead of a hand-written string
• AGENT_REMINDERS was moved before the periodic reminder block to reflect the dependency order
• Tests in prompt.test.ts and agent.test.ts updated to assert on the actual AGENT_REMINDERS wording

This means both reminder channels now use identical phrasing and can't drift apart as entries are added or changed in the future.

Concern #2 (no opt-out path for OPENCLI_SYSTEM_MD) is unchanged — still a lower-priority follow-up as noted in the review.

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[zjshen14]

Re-review following the wording fix in commit 35f9e7c. PERIODIC_REMINDER_TEXT is now derived from AGENT_REMINDERS.map((r) => r.text).join("; ") — both reminder channels share the same text and can't drift apart as entries are added. The tests correctly assert on the actual AGENT_REMINDERS wording (checking for "never commit or push without an explicit user request"). CI is all green, mergeable_state is clean. Both prior concerns from the June 4 and June 19 reviews are fully resolved. Merging.

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