Feature request: Session Cost including subagent/Task cost (option or new widget)

[lala74]

Problem

The session-cost widget shows cost.total_cost_usd from the status line stdin. In current Claude Code, subagent/Task runs are stored as separate transcripts (projects/<proj>/<session>/subagents/agent-*.jsonl), and Claude Code's total_cost_usd only reflects the main transcript. So the cost value stays flat while subagents burn tokens — users running heavy Agent/Task workloads (parallel subagents, background tasks) see a misleadingly low cost.

Why ccstatusline can do this

ccstatusline already reads those subagents/*.jsonl files for the speed-metrics widgets (getReferencedSubagentIds / includeSubagents). The same transcript walk exposes each subagent's usage token counts. Cost can be computed from tokens × model pricing (as the closed #18 ccusage-style widgets proposed) and combined with the stdin total_cost_usd.

Proposal

Two possible shapes (either or both):

A. Option on existing session-cost widget — e.g. includeSubagents: true that adds subagent token cost to the displayed total.

B. New dedicated widget — e.g. session-cost-with-subagents (or total-cost) that always shows main + subagent cost, leaving the existing session-cost as main-only. This keeps the two values distinguishable for users who want both segments on the line:

$2.45 main  +  $1.10 agents  =  $3.55 total

Option B avoids changing existing behavior and lets users place main-only and combined side by side.

Environment

• ccstatusline 2.2.22
• Claude Code stores subagents in a separate subagents/ dir (no isSidechain inlining in the main transcript), which is why total_cost_usd excludes them.

[lala74]

Opened #475 implementing the agent-count piece of this idea — an agent-count widget showing subagents spawned this session (relates to #299).

Note the scope split:

• feat: add Session Cost (with subagents) widget #475 (this PR) = count of subagents spawned this session, derived from on-disk subagent transcripts.
• This issue's original ask = subagent cost rolled into the Session Cost widget — still open. That needs token→price computation over the subagent transcripts (cf. closed Add ccusage-like cost tracking widgets #18 ccusage-style widgets), which feat: add Session Cost (with subagents) widget #475 does not address.

Leaving this issue open for the cost portion.

[lala74]

Update: #475 now implements the cost half of this issue directly — a session-cost-total widget that adds subagent cost (priced from the on-disk subagent transcripts) on top of cost.total_cost_usd. My earlier comment about it being an agent-count widget is superseded; that idea was dropped in favor of the cost total.

So #475 closes the cost portion of this issue.