feat(harness-state): map pi events to v3

[schickling-assistant]

Problem

The pi channel lacks typed failure edges, and the prior 0.84.2 pin does not emit the typed compaction-failure event.

Goal

Negotiate protocol 2, map real pi event shapes, and retain protocol-1/v2 compatibility.

Decisions

• keep scalar hello protocol 1 plus offered [1,2]
• scan the real agent_end.messages tail
• clear only on stop or length; interrupted and incomplete endings stay silent
• raise compaction faults only when aborted === false
• represent ask capability as unknown and conversation as unsupported

Verification

• cargo test -p st2 --lib pi_channel::
• TypeScript gate and extension smoke against pi 0.84.4
• nix flake check --no-build
• Linux and Darwin CI passed
• flat source hash independently verified
• independent review completed with no remaining P0-P2 findings

Complexity

The protocol offer preserves old assets while enabling the typed plane.

Concerns

No writer activation in this PR.

Friction & bottlenecks

An inherited invariant row cites a resource test absent from #464; pi proof references resolve.

Follow-ups

#479 activates the integrated writer.

References

Depends on #470.

Posted on behalf of @schickling

field	value
agent_identity	dev3.direct.omp.9exwnk6h
session	dev3.9exwnk6h
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.1.7
agent_runtime	OMP 18.1.7
tooling_profile	dotfiles@931583a

[schickling-assistant]

Parking this PR (closed, branch kept) per decision Q1 incidents-first in seat dev3.direct.omp.43sz6ujq (record 2we9ak / answer 8b0ow1, 2026-09-06): the harness-state v3 stack ships only once a named consumer requirement or incident calls for the fault/ask/conversation axes.

Findings that shape re-entry (evidence: an independent 12-reviewer pass + orchestrator reports in the orch worktree, tmp/orch-reconcile/reports/{stack,migrations,complexity}.md):

• The stack bases on the CLOSED Implement immutable agent IDs and mutable addresses coherently #464 branch; the harness-state.v2 it supersedes exists only there, never on main. Re-entry rehomes feat(harness-state): add v3 reader foundation #469's real content (one commit, df327b5, +2773/-120) onto main after Split the agent route from its durable key: mutable address, optional immutable id #468 -> feat(agent): mutable address, immutable positional identity #467, and drops the v2 layer (SCHEMA_V2, EMIT_SCHEMA_V2, RecordSubject, v2 fixtures).
• Policy Q2 previous-release-rollback: writers emit the newest format only; no compile-time gates (EMIT_SCHEMA_*, writes_condition_axis()) and no rollback floors; readers keep tolerant arms with a named deletion trigger.
• Activation re-enters as an activation-only PR (schickling assistant/2026 09 05 harness v3 activation #479's own delta is +916/-318); schickling assistant/2026 09 05 harness v3 activation #479 as opened is the union of feat(delivery): add durable delivery ledger #471 + five adapters and would be reviewed twice.
• feat(delivery): add durable delivery ledger #471 (delivery ledger) is NOT parked: it is independent of v3 and will be rebased onto main by the integrator lane.

Posted on behalf of @schickling

field	value
agent_identity	dev3.direct.omp.43sz6ujq
session	dev3.43sz6ujq
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.1.7
agent_runtime	OMP 18.1.7
tooling_profile	dotfiles@39a19af