feat(tui): show usage by routed model

[lambertjosh]

Why

The TUI sidebar shows aggregate token usage, but it does not explain which concrete routed models consumed those tokens or incurred the cost. Delegated subagent usage is also omitted from the active session summary.

What changed

The sidebar now shows cumulative input, output, reasoning, cache read/write, cache rate, and direct cost, followed by the same metrics grouped by concrete routed model. Aggregation covers the complete top-level session tree, including subagents, and sums step costs directly to avoid double counting propagated child costs.

The aggregation is exposed through the local CLI API and implemented in Kilo-owned code to minimize upstream merge conflicts. Older steps without routed model metadata fall back to the assistant message model.

Dependency

This builds on the routed step model metadata merged in #11556. The branch is rebased directly onto main.

[lambertjosh]

[kilo-code-bot]

Code Review Summary

Status: 1 Issue Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/test/kilocode/server/httpapi-public.test.ts	169	Removing the nextBillingAt assertion drops the only regression check that the generated public OpenAPI keeps this field nullable, so CI would no longer catch the wire-contract narrowing that was just fixed in this PR.

Fix these issues in Kilo Cloud

Files Reviewed (1 files)

• packages/opencode/test/kilocode/server/httpapi-public.test.ts - 1 issue

Previous Review Summaries (9 snapshots, latest commit 611fcb1)

Current summary above is authoritative. Previous snapshots are kept for context only.

Previous review (commit 611fcb1)

Status: No Issues Found | Recommendation: Merge

Files Reviewed (5 files)

• packages/opencode/src/cli/cmd/generate.ts
• packages/opencode/src/kilocode/server/httpapi/public.ts
• packages/opencode/test/kilocode/server/httpapi-public.test.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json

Previous review (commit 92a756e)

Status: 2 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	1

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/sdk/openapi.json	13081	nextBillingAt was regenerated as string even though the source Kilo gateway schema still allows `string

SUGGESTION

File	Line	Issue
packages/sdk/openapi.json	15227	The new sessionModelUsage code sample is missing the closing quote in the import path, so the published JavaScript example is not copy-pasteable.

Fix these issues in Kilo Cloud

Files Reviewed (15 files)

• .changeset/show-routed-step-models.md
• packages/opencode/src/cli/cmd/tui/routes/session/usage.ts
• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/src/kilocode/server/httpapi/groups/kilocode.ts
• packages/opencode/src/kilocode/server/httpapi/handlers/kilocode.ts
• packages/opencode/src/kilocode/session/model-usage.ts
• packages/opencode/test/cli/tui/usage.test.ts
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts
• packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
• packages/opencode/test/kilocode/server/httpapi-public.test.ts
• packages/opencode/test/kilocode/session-model-usage.test.ts
• packages/sdk/js/src/v2/gen/sdk.gen.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json - 2 issues

Previous review (commit 96a0f3d)

Status: 1 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/plugins/sidebar-usage.tsx	127	Using Model.name(...) directly skips the routed-model normalized-id fallback, so versioned Kilo model IDs can still render as raw snapshot slugs instead of the compact display name.

Fix these issues in Kilo Cloud

Files Reviewed (1 files)

• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx - 1 issue

Previous review (commit 6e387f5)

Status: 1 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/sdk/openapi.json	15197	The generated JavaScript code sample for sessionModelUsage is missing a closing quote in the import path, so the published OpenAPI example is invalid.

Fix these issues in Kilo Cloud

Files Reviewed (15 files)

• .changeset/show-routed-step-models.md
• packages/opencode/src/cli/cmd/tui/routes/session/usage.ts
• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/src/kilocode/server/httpapi/groups/kilocode.ts
• packages/opencode/src/kilocode/server/httpapi/handlers/kilocode.ts
• packages/opencode/src/kilocode/session/model-usage.ts
• packages/opencode/test/cli/tui/usage.test.ts
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts
• packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
• packages/opencode/test/kilocode/server/httpapi-public.test.ts
• packages/opencode/test/kilocode/session-model-usage.test.ts
• packages/sdk/js/src/v2/gen/sdk.gen.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json - 1 issue

Previous review (commit 41e9082)

Status: No Issues Found | Recommendation: Merge

Files Reviewed (3 files)

• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts

Previous review (commit 78cc8da)

Status: 1 Issue Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/plugins/model-usage.ts	35	Compact sidebar labels now drop provider identity for non-Kilo rows, so distinct routed models can render under the same visible name.

Fix these issues in Kilo Cloud

Files Reviewed (3 files)

• packages/opencode/src/kilocode/plugins/model-usage.ts - 1 issue
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts

Previous review (commit b5dad58)

Status: 1 Issue Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/session/model-usage.ts	93	Step-level routed-model attribution still disagrees with kilo stats --models, so the CLI can report different per-model usage for the same sessions.

Fix these issues in Kilo Cloud

Files Reviewed (5 files)

• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/src/kilocode/session/model-usage.ts - 1 issue
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts
• packages/opencode/test/kilocode/session-model-usage.test.ts

Previous review (commit b24464c)

Status: 4 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	3
SUGGESTION	1

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/plugins/sidebar-usage.tsx	52	Global session events refetch usage for unrelated session activity, causing avoidable full-tree queries for the visible sidebar.
packages/opencode/src/kilocode/session/model-usage.ts	87	Step-level routed-model attribution now disagrees with kilo stats --models, so the CLI can report different per-model usage for the same sessions.
packages/opencode/src/kilocode/session/model-usage.ts	131	Looking up sessions only by ctx.project.id can return 404 for sessions that remain visible via directory-based session-family semantics after a project-id change.

SUGGESTION

File	Line	Issue
packages/opencode/src/kilocode/plugins/sidebar-usage.tsx	19	Reuse the routed-model display helper so long providerID/modelID values do not overflow the narrow sidebar unnecessarily.

Fix these issues in Kilo Cloud

Files Reviewed (15 files)

• .changeset/show-routed-step-models.md
• packages/opencode/src/cli/cmd/tui/routes/session/usage.ts
• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx - 2 issues
• packages/opencode/src/kilocode/server/httpapi/groups/kilocode.ts
• packages/opencode/src/kilocode/server/httpapi/handlers/kilocode.ts
• packages/opencode/src/kilocode/session/model-usage.ts - 2 issues
• packages/opencode/test/cli/tui/usage.test.ts
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts
• packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
• packages/opencode/test/kilocode/server/httpapi-public.test.ts
• packages/opencode/test/kilocode/session-model-usage.test.ts
• packages/sdk/js/src/v2/gen/sdk.gen.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json

Previous review (commit a70121d)

Status: No Issues Found | Recommendation: Merge

Files Reviewed (15 files)

• .changeset/show-routed-step-models.md
• packages/opencode/src/cli/cmd/tui/routes/session/usage.ts
• packages/opencode/src/kilocode/plugins/model-usage.ts
• packages/opencode/src/kilocode/plugins/sidebar-usage.tsx
• packages/opencode/src/kilocode/server/httpapi/groups/kilocode.ts
• packages/opencode/src/kilocode/server/httpapi/handlers/kilocode.ts
• packages/opencode/src/kilocode/session/model-usage.ts
• packages/opencode/test/cli/tui/usage.test.ts
• packages/opencode/test/kilocode/cli/cmd/tui/model-usage.test.ts
• packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
• packages/opencode/test/kilocode/server/httpapi-public.test.ts
• packages/opencode/test/kilocode/session-model-usage.test.ts
• packages/sdk/js/src/v2/gen/sdk.gen.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json

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_{Reviewed by gpt-5.4-2026-03-05 · Input: 63K · Output: 9.1K · Cached: 261.6K}

_{Review guidance: REVIEW.md from base branch main}

[lambertjosh]

@alex-alecu - I think this is ready for re-review