deps(deps): bump github.com/sky-valley/pi from 0.84.19 to 0.84.20

[dependabot]

Bumps github.com/sky-valley/pi from 0.84.19 to 0.84.20.

Changelog

Sourced from github.com/sky-valley/pi's changelog.

v0.84.20

Upstream sync 56f3f33a9 → 853a80d26 (pi 0.84.4). 7 first-parent changes, no merges: 2 ports, 2 port-but-queued, 3 n/a, 0 decide. Release v0.84.4 crossed, so the catalog was regenerated from the integrity-verified build — 558,804→563,988 B, 1312→1290 models across an unchanged 39 providers (+57/−79, 227 changed) — with the decision made by executing JSON.stringify(MODELS) against both builds rather than by reading git, and endpoint-pinned at both ends so the ported diff is exactly the upstream release diff. Both review gates re-derived it independently. The regen drains the entire three-item generator queue that had accumulated since 0.84.3, and the queue does not reopen — no generator delta landed this cycle. There is no schema drift at any level, and compat.allowedFallbackModels keeps its two anthropic entries and their chains, so the refusal-fallback path is unaffected.

Behaviour: the agent loop prepares each turn immediately before its request (upstream #8782) instead of right after the previous turn ended. Three consequences reach the public API. ShouldStopAfterTurn now runs first, on the context of the turn that just completed. PrepareNextTurn runs only when another turn will actually happen, so it no longer fires after a final or terminating turn — if you were doing end-of-run work there, move it to agent_end handling. And because preparation can be long-running, steering queued while it ran is picked up before the turn starts, so a message typed during compaction reaches the turn it was typed for rather than the one after. Both hooks gained doc comments recording the new ordering; upstream filed the same change under Breaking Changes.

The coding-agent half of that upstream fix needed no port: the port drives auto compaction through a per-request TransformContext hook, which already fired before every provider request including post-tool ones — the property upstream was adding. One residual is recorded as a deliberate divergence in UPSTREAM.md: because the port compacts inside the request rather than in prepareNextTurn, steering typed during compaction lands one turn later than in pi, costing one extra provider round-trip. It is a tripwire on the compaction-placement ruling, not a defect.

Two upstream changes are in scope but have no Go base yet and were queued rather than ported: a Mistral tool-call chunk-merging fix (Scope queue entry 6) and an image-model catalog refresh (entry 3).

Commits

• 886ece5 docs(upstream): advance pin to 853a80d26 (2026-08-29 cycle — 2 ports, release...
• 3ad9fe5 port(agent): review fixes for the turn-preparation reorder
• b344142 difftest: re-pin to 853a80d26 / pi-ai 0.84.4
• e1e8cdb port(agent): prepare the next turn immediately before its request (upstream 5...
• 08f5bed port(ai): regenerate model catalog from pi 0.84.4 (upstream b79e4cc83)
• 768d336 docs(upstream): rewrite entry 8's slice table against what 8b actually shipped
• ceba850 docs(upstream): advance pin to 56f3f33a9 (2026-08-28 cycle — 0 ports, no rele...
• edaa03c difftest: re-pin to 56f3f33a9
• 1f49233 port(coding): wire the shell and grep seams — all seven tools now pluggable
• cd0e3b9 port(coding): fix ops resolution semantics; wire ls and find
• Additional commits viewable in compare view

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Superseded by #55.