Subprocess tool-use / thinking / usage / compact-boundary parity with SDK (agent-sidepanel-v2 Increment 2 follow-up)

[Luis85]

Context

PR #378 (StreamDelta union extension) adds thinking, tool-use-start, tool-use-input-delta, tool-use-stop, compact-boundary, and usage variants — fully wired on the SDK path (ClaudeCliAdapter._dispatchMessage).

The subprocess path (ClaudeSubprocessAdapter._handleNdjsonLine) was deferred:

Deferred to follow-up PRs:

Subprocess parity — ClaudeSubprocessAdapter._handleNdjsonLine uses a different wire format (system/init / assistant/message / result, not stream_event content blocks). Extending it for tool-use parity needs the CLI's actual --include-partial-messages event surface verified against a real binary.

— from PR #378 description.

This issue tracks closing that gap so the subscription transport gets the same tool-use / thinking / usage / compact-boundary coverage as the SDK transport.

Why it matters

Today, a user on the subscription transport (transportKind === 'subscription' → ClaudeSubprocessAdapter) sends a turn that produces tool calls or extended thinking, and the chat UI:

• Sees only text deltas (existing behaviour) — falls back to the pre-extension experience.
• Misses tool-call cards, thinking-block panels, usage telemetry, compaction notices.

That's a transport-dependent UX regression — the SDK transport user gets one experience, the subscription user gets another.

Wire format gap

The SDK adapter already maps Anthropic stream_event content blocks:

• system + subtype === 'init' → session-id
• system + subtype === 'compact_boundary' → compact-boundary
• stream_event + content_block_start (type === 'tool_use') → tool-use-start
• stream_event + content_block_delta:
  • text_delta → text
  • thinking_delta → thinking
  • input_json_delta → tool-use-input-delta
• stream_event + content_block_stop (tool_use only) → tool-use-stop
• stream_event + message_start / message_delta + .usage → usage

The subprocess emits a different envelope when --output-format stream-json --include-partial-messages is set. Need to verify the actual event names against a current claude binary, then implement the same dispatcher in _handleNdjsonLine.

Plan

Step 1 — capture real wire output

Run locally:

echo "Use the Bash tool to list /tmp" | claude -p \
  --output-format stream-json \
  --verbose \
  --include-partial-messages \
  --allowedTools Bash \
  > /tmp/wire.ndjson 2>&1

Note: that command will trigger the real Anthropic Terms of Service flow. Run it against a permissive sandbox vault.

Document the event names + payload shapes in inputs/subproc-tool-wire-2026-XX/ so future contributors don't have to re-capture.

Step 2 — extend _handleNdjsonLine

Mirror the SDK dispatcher. Use the same blockId = ${turnId}-${index} pattern from PR #378 for tool blocks. Surface the same StreamSink (or createPushChannel) helper.

Watch out for:

• The subprocess buffers chunks across \n boundaries — already handled by the existing stdoutBuffer.
• --include-partial-messages may produce duplicate emits (content_block_delta followed by content_block_stop with the same final fragment); Claudian PR #510 fixed similar dedup. Add a per-blockId "already-stopped" guard.

Step 3 — tests

• tests/infrastructure/obsidian/ClaudeSubprocessAdapter.deltaExtension.test.ts — one case per new variant. Fixtures from the wire capture in step 1.
• Extend tests/infrastructure/obsidian/ClaudeSubprocessAdapter.streaming.test.ts with the same coverage as the SDK version on PR feat(agent): extend StreamDelta with thinking/tool-use/compact/usage variants (PR-ASV-2-delta) #378.

Step 4 — MessageList.vue scroll watcher

PR #379 added a tool-call input-growth observer to the scroll watcher. Verify it works against the subprocess transport too (same streamingToolCalls map → same observable).

Acceptance

• Wire capture documented under inputs/.
• ClaudeSubprocessAdapter._handleNdjsonLine emits all new StreamDelta variants.
• Block dedup guard for content_block_stop-after-_delta race.
• Tests for every new variant on the subprocess adapter.
• All 1500+ existing tests still green.

References

• PR feat(agent): extend StreamDelta with thinking/tool-use/compact/usage variants (PR-ASV-2-delta) #378 (SDK side, base for parity).
• PR feat(agent): ToolCallBlock + ThinkingBlock renderers (PR-ASV-2-tool-rendering) #379 (tool-call renderers — consumes the new variants).
• Comparative review (top-2 + top-3 gaps).
• Claudian PR #510 (stream dedup pattern).
• specs/agent-sidepanel-v2/workflow-state.md → Increment 2+ research wave.
  ["enhancement"]