feat(harness): stop sharing agent $ cost with the client

[odtorres]

What & why

The harness computed the LLM dollar cost (cost_usd) per turn and streamed it to the client in the usage.recorded SSE event, where miot-chat rendered it in the TUI footer as $0.0123. We don't want tenants to see how much each query costs us.

This stops the dollar cost from ever leaving the server, while keeping it tracked internally so we still measure our own spend.

Changes

Boundary fix (backend)

• miot-harness/.../observability/callbacks.py — no longer attaches cost_usd to the usage.recorded event. The cost is still computed and kept as the server-side span attribute (gen_ai.usage.cost_usd), so eval reports and provenance logs are unchanged.

Client cleanup (token counts untouched)

• miot-harness-client/src/types.ts — dropped cost_usd from UsageRecordedData.
• miot-chat/.../session/types.ts — removed costUsd / lastCostUsd from UsageTotals + ZERO_USAGE.
• miot-chat/.../transcript/project.ts — removed cost accumulation.
• miot-chat/.../chrome/FooterLine.tsx — footer now shows 1234→56 with no $ figure.

Left intentionally untouched (internal-only): report.py, run_golden.py eval totals, provenance.py plan_cost, and the Postgres EXPLAIN total_cost (a query-planner estimate, not dollars).

Verification

• Harness: test_usage_recorded_event.py + test_callbacks.py → 10 passed (event omits cost_usd; span attribute retained).
• TUI: FooterLine.test.tsx + transcript.project.test.ts → 29 passed (footer shows tokens, no $).
• tsc --noEmit on miot-chat and miot-harness-client → exit 0.
• Grep confirms no cost_usd/costUsd references remain in turbo-repo.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Removed dollar-cost values from client-facing usage events and summaries.
  • Updated usage tracking to keep token counts and agent details without showing pricing information.
  • Simplified the TUI footer so usage now displays token totals only, with no dollar amount.
  • Adjusted related test coverage to reflect the new usage display and event payload behavior.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: d8c169e9-5583-48b5-8b6e-9a5e017f5ff5

📥 Commits

Reviewing files that changed from the base of the PR and between 9e481d3 and fa0ecd4.

📒 Files selected for processing (1)

• turbo-repo/packages/miot-chat/src/tui/__tests__/transcript.project.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch based/not-showing-cost

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[odtorres]

Tracked by #872.

[coderabbitai]

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Failed to replace (edit) comment. This is likely due to insufficient permissions or the comment being deleted.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@turbo-repo/packages/miot-chat/src/tui/__tests__/transcript.project.test.ts`:
- Around line 478-479: Update the transcript projector test in
transcript.project.test to assert that client-side usage totals do not include
both monetary fields: keep the existing costUsd check and add a matching absence
assertion for lastCostUsd on s2.usageTotals. Use the existing usageTotals
expectation block in the test to ensure the client contract stays free of both
money-related properties.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 0b128f6c-ef03-4136-a595-871e621d3918

📥 Commits

Reviewing files that changed from the base of the PR and between bb37f23 and 9e481d3.

📒 Files selected for processing (8)

• miot-harness/src/miot_harness/observability/callbacks.py
• miot-harness/tests/observability/test_usage_recorded_event.py
• turbo-repo/packages/miot-chat/src/tui/__tests__/components/FooterLine.test.tsx
• turbo-repo/packages/miot-chat/src/tui/__tests__/transcript.project.test.ts
• turbo-repo/packages/miot-chat/src/tui/chrome/FooterLine.tsx
• turbo-repo/packages/miot-chat/src/tui/session/types.ts
• turbo-repo/packages/miot-chat/src/tui/transcript/project.ts
• turbo-repo/packages/miot-harness-client/src/types.ts

💤 Files with no reviewable changes (2)

• turbo-repo/packages/miot-harness-client/src/types.ts
• turbo-repo/packages/miot-chat/src/tui/transcript/project.ts

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud