feat(wire,kernel,conversation-store): step grouping via stepId for batched tool calls

Expose a per-step grouping key so a client can render a model's batched/parallel
tool calls (those emitted in one step) as one unit, on both the live stream and
replayed history. Key = branded StepId, derived turnId#stepIndex (0-based).

- [email protected]: required stepId on Turn{Tool,ToolResult}Event; optional stepId on
  Tool{Call,Result}Chunk (generation provenance on the chunk, not the StoredChunk
  envelope — StoredChunk unchanged). [email protected] (re-export bump).
- kernel-runtime: mint stepId per step; stamp on tool chunks + tool events.
- conversation-store: chunk-carried stepId round-trips append/load/loadSince for
  free; reconcile copies it onto synthesized (interrupted) results.
- cli: stepId added to event test fixtures (renderer unchanged).

typecheck clean; 509 vitest + 89 bun; biome 0/0. FE courier reply + reference
snapshots regenerated in ../dispatch-web.

1 files changed, 1 insertions, 0 deletions

diff --git a/GLOSSARY.md b/GLOSSARY.md
index 42cd557..0ec7ea2 100644
--- a/GLOSSARY.md
+++ b/GLOSSARY.md
@@ -17,6 +17,7 @@
 | **conversationId** | The string identifier for a conversation. Threads multi-turn history; the `/chat` request field that continues an existing conversation. | tabId, sessionId, chatId |
 | **turn** | One user message → assistant response cycle (may span multiple steps). | — |
 | **step** | One LLM round-trip within a turn (may emit multiple tool calls). | iteration |
+| **stepId** | The identifier of a step, stamped on each `tool-call`/`tool-result` event and tool chunk it produces, so a client groups a parallel/batched tool-call set by equality. Branded `StepId`; the runtime derives it deterministically as `<turnId>#<stepIndex>` (0-based). Generation provenance carried ON the tool chunk (unlike `seq`, which is a store-assigned sync cursor on the `StoredChunk` envelope). Treat as opaque. | batchId, step index (as the wire key) |
 | **tool call** | A model's request to run a tool within a step. | function call (when meaning a tool call) |
 | **chunk** | One ordered piece of a message (text, thinking, tool-call/result, etc.), append-only in the log. | block, segment |
 | **seq** | The monotonic, gap-free, per-conversation sequence number stamped on each chunk as it is appended to the log. The sync cursor: a client requests `?sinceSeq=N` to fetch only newer chunks. Storage/sync metadata, never message content. | cursor (when meaning the number), offset, index |