fix: respond to actionable bot self-reviews instead of self-loop-exiting

[tend-agent]

Closes #761.

Problem

When tend-review and the PR author are the same bot account (tend-on-tend, or any consumer using one bot for both authoring and reviewing), an actionable self-review is silently swallowed. tend-mention triggers correctly and Claude runs to completion, but the run reads a CHANGES_REQUESTED / COMMENTED-with-findings review on the bot's own PR, treats it as the bot talking to itself, and exits without acting. The finding only gets actioned when a human asks by hand.

The verify gate is already correct — it fires should_run=true for an actionable self-review; #749 only skips empty-body APPROVED ones. The silent exit comes from two prompt-layer guards with no reviewer/author carve-out:

• The system-prompt self-loop guard was absolute: "before responding to a comment or review, confirm the triggering actor isn't the bot itself."
• The non-mention pull_request_review prompt branch said only "respond appropriately … if the review approves or is between humans, exit silently" — it never named the bot-authored-review case, so it read as "between humans / self."

running-in-ci's Self-conversation Guard already documents the exception ("only respond if there is a distinct role boundary, e.g. you are the reviewer on your own PR"), but neither of the two surfaces above carried it, and the system prompt wins.

Fix — both surfaces #761 names

1. shared/system-prompt.md — the self-loop guard now carves out the role boundary: an actionable review the bot's review workflow posted on the bot's own PR (CHANGES_REQUESTED, or COMMENTED with findings/questions) is reviewer-to-author feedback, not a self-loop — address it. A bot approval or an ask-free bot comment still exits silently.
2. generator/src/tend/templates/mention.yaml.j2 — the non-mention review branch now positively instructs that a review your own review workflow posted on your own PR is your reviewer role speaking, so action it; exit silently only for a plain approval or a review with no actionable content.

The system prompt is composed at runtime by all three harness actions, so no workflow regeneration is needed for surface 1; surface 2 regenerates the mention regtest snapshots (updated here). Reaches adopters at the next release. All 256 generator tests pass.

Relationship to other issues/PRs

• tend-mention: bot-authored review with actionable findings on bot's own PR is silently swallowed by self-loop guards #761 — the tracking issue this closes (filed in parallel from the same worktrunk thread).
• tend-review: short-circuit no-op self-review of bot-authored PRs before reading the diff #607 / fix(mention): skip no-op tend-mention session on bot's own comments #751 — the opposite premise: suppress no-op bot self-comments / empty self-approvals at the gate. This change is about an actionable self-review that found a real bug. Complementary — different event types and layers.

Loop consideration

If addressing the review pushes a commit, synchronize re-runs tend-review, which posts a fresh review — the same re-trigger loop that already exists for human-authored reviews, bounded by review eventually approving (terminal, gate-skipped), the mention dedup guard, and the findings actually getting resolved. Triggering here is the intended behavior.

Requested by @max-sixty in max-sixty/worktrunk#3394: "let's fix that … We need to trigger in this case."

[tend-agent]

The self-review carve-out reads well and I verified the layering: the verify gate already lets an actionable bot self-review through (it skips only approved + empty-body), and the in-process render preserves the em-dash — the ? in the regenerated snapshots is the usual pytest-regtest non-ASCII normalization, consistent with the em-dashes already in that file, so no functional concern there.

One thing the rewrite dropped, though: the review branch lost its bystander off-ramp. The old text was "If the review approves or is between humans, exit silently"; the new text is "Exit silently only for a plain approval or a review with no actionable content." The only forecloses the between-participants case — a human requesting changes on another human's PR where the bot previously participated (so the verify gate fires should_run=true) now falls under "requests changes → respond appropriately (make the change and push)", pulling the bot into a review it's a bystander to.

The sibling comment-fallback branch right below still keeps its off-ramp ("If the conversation is between other participants, exit silently"), so the two fallbacks are now asymmetric — which reads as an unintended side effect of the rewrite rather than an intended scope change. Suggestion inline restores the bystander exit while keeping the self-review carve-out.

Note: applying the suggestion changes the source template only — the 3 test_workflow_*_regtest[mention] snapshots need regenerating (uv run pytest tests/ -k mention --regtest-reset) in the same commit or the regtests fail.

[max-sixty]

but then the trigger hasn't changed; only the guidance?

I'm less of a fan of the guidance; it seems overly verbose

[tend-agent]

Right — the trigger and the verify gate are unchanged. The gate already fired should_run=true for these (#749 only skips empty-body APPROVED self-reviews); the bug was purely at the prompt/guidance layer, so guidance is all that moved.

Trimmed both surfaces in 36f7684 — same behavior, fewer words:

• system-prompt guard: 8 lines → 6, folded the carve-out into the guard sentence itself.
• mention review branch: dropped the parenthetical and the "your reviewer role speaking" restatement, kept the "including when you authored the review" clause and the bystander off-ramp.

256 tests pass, mention regtest snapshots regenerated.