2026.10.04 - Phase 4: Pi DCP Lifecycle Integration

[lanhhoang]

• Lifecycle-aware compress registration — registered at extension creation with defaultActive: false, schema refreshed at session_start.
• Branch-scoped suppression memory — remembers the tool's prior active state across overlapping reasons and clears on session/tree changes.
• Implicit fresh-session activation — selects compress once on the first session_start when no loadout is declared.
• Reconciled lifecycle ordering — session_start and session_tree restore state, establish model identity, then reconcile.
• Structured dcp prompt section — before_agent_start sets or removes only the dcp section.
• Run-boundary prompt reloads — custom prompts refresh once at each before_agent_start.
• Guidance follows the selection — dcp section and nudges are hidden whenever compress is inactive.
• Pure capability calculation — new getDcpCapabilities for pipelineEnabled and compressionEnabled.
• Defensive authorization — tool_call and execute reject every policy reason.
• Command gating — mutating commands require pipeline eligibility; dcp:compress needs compression and an active tool and never activates it.
• Typed harness and SDK fixture — createExtensionHarness plus an offline createAgentSession contract test.
• 0.9.0 release — version bump, CHANGELOG, README, and regenerated schema.
• Plan and design review fixes — phase plan and design spec tightened to match the implementation.