docs(subsystems): open core.md on agent creation/ownership and the Agent contract; enforce a complete folder index

core.md claimed to be the packages/core reference but opened on repo-wide type patterns and never documented the ownership vocabulary: AgentHandle, CreateAgentOptions, ResumeAgentOptions, and AgentFactory were TYPE_LINK_EXEMPTIONS pointing at a package README, invisible to the folder that calls itself the type reference. The page now reads spine map -> creation and ownership (AgentHandle pasted; the options and factory summarized with links into the generated registry section) -> the Agent handle (AgentStatus, AgentOptions, SteeringOutcome, SteeringReceipt, and SettleReason now pasted; the one settlement prose wall split by topic; delivery vocabulary ordered as a message travels) -> initiator -> interception -> a Sessions summary -> the ToolDefinition pointer -> an explicitly framed repo-wide patterns tail (the ...Map pattern, branded ids). The duplicate SessionEvent paste is gone -- session.md owns it and LINK_MAP follows -- the four ownership types moved from TYPE_LINK_EXEMPTIONS into LINK_MAP -> core.md, and three dead LINK_MAP entries (ContinuationDecision, ContinuationStop, HookContext) no longer name types absent from the source tree. The "what this page owns" meta-section folds into the intro.

The subsystems README index silently lost tasks.md and session-reference.md on both language sides during a base absorption; the rows are restored and scripts/project-doc-site.spec.ts now fails when any page misses either side of the index (proven red on a removed row). tools.md links ToolSchema to its llm-streaming.md declaration instead of calling it core; subagent.md links AgentHandle and CreateAgentOptions.seed to the new section. A new Agent Note records the package-anchored page-scoping decision; the 2026-06-20 catalog note marks its spine-vs-seam rule superseded as the page-scoping rule while keeping the type-equiv mechanism current, and docs/AGENTS.md cites the new note.

docs/subsystems/subagent.md

@@ -133,7 +133,7 @@ persisted Session
 | `waiting` | wake the same Activation |
 | no Activation | cold-resume a new Activation |
 
-`running` means the Agent has an active admission or turn, or waking inbox work; `waiting` means it is quiescent but still owns at least one child Activation that has not completed disposal; `settled` means quiescent with every owned child disposed, at which point the manager disposes the `AgentHandle` and removes the Activation. The manager derives these internal conditions from Agent quiescence and the owned-child set rather than maintaining a second execution state machine.
+`running` means the Agent has an active admission or turn, or waking inbox work; `waiting` means it is quiescent but still owns at least one child Activation that has not completed disposal; `settled` means quiescent with every owned child disposed, at which point the manager disposes the [`AgentHandle`](core.md#creation-and-ownership) and removes the Activation. The manager derives these internal conditions from Agent quiescence and the owned-child set rather than maintaining a second execution state machine.
 
 The Agent inbox is the only queue. Every continuation message becomes one `Agent.followup()` FIFO turn, so accepted messages have one observable order and a follow-up cannot redirect a turn already underway. Successful delivery returns the accepted `MessageId`; the existing `agent/inbox/enqueue`, `agent/inbox/dequeue`, and `agent/inbox/discard` events remain the message-lifecycle observations, and the continuation layer defines no subagent-specific delivery route.
 
@@ -432,7 +432,7 @@ Provider `start()` fulfills with a published run. The service mints a unique `ru
 The spawn and fork backends create an ordinary one-shot agent through `parent.ctx`, pass cancellation into core creation, and dispose through `AgentHandle`; a continuable child is instead created by the continuation manager through its own activation-owner scope. Provider removal blocks new starts without revoking accepted runs. Each child gets a new flat scope rather than inheriting parent registrations. Depth and fork seeding reuse existing agent and session vocabulary:
 
 - **Delegation depth** is durable `SessionHeader.delegationDepth` plus the merge-extensible runtime field `AgentOptions.subagentDepth`; absence means top-level depth zero, and the greater present value is authoritative. The seam owns both fields — the loop neither sets nor reads them — so an in-process child persists parent depth + 1, cold resume cannot lower it, and every start rejects a derived depth outside the safe-integer domain or above a defined absolute `request.maxDepth` cap.
-- **Fork seeding** uses `CreateAgentOptions.seed` (a `SessionEvent[]` prefix threaded through `AgentLoop.createAgent` → `ctx.sessions.prepare({ seed })`, the same primitive `ctx.agents.resume()` uses). The fork backend passes a *balanced completed-turn prefix* of the parent's log — the parent's events up to and including its last `turn/end` — so the seed is contiguous-from-0 and the [invariants](../../packages/support/invariants) replay accepts it (the in-flight, unbalanced turn is excluded).
+- **Fork seeding** uses [`CreateAgentOptions.seed`](core.md#creation-and-ownership) (a `SessionEvent[]` prefix threaded through `AgentLoop.createAgent` → `ctx.sessions.prepare({ seed })`, the same primitive `ctx.agents.resume()` uses). The fork backend passes a *balanced completed-turn prefix* of the parent's log — the parent's events up to and including its last `turn/end` — so the seed is contiguous-from-0 and the [invariants](../../packages/support/invariants) replay accepts it (the in-flight, unbalanced turn is excluded).
 
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