Greptile Summary

This PR fixes a context window display bug (#46632) where the chat UI and /usage slash command were showing inflated token counts by reading session.inputTokens (cumulative across all API calls in a run) instead of session.totalTokens (the actual current context window size from the last API call). It also introduces slash-command-executor.ts as a new dedicated module for slash command logic and adds a comprehensive test suite covering both the browser context-notice rendering and the node-side slash command execution.

Key changes:

• chat.ts — renderContextNotice now reads session?.totalTokens instead of session?.inputTokens, fixing the "100% / 200k" false positive when cumulative tokens exceeded the context limit but actual context usage did not.
• slash-command-executor.ts — New file; executeUsage computes the context percentage from totalTokens via const total = session.totalTokens ?? input + output.
• Tests — New browser tests validate the 85% threshold and the totalTokens-vs-inputTokens distinction; new node tests cover all slash command paths.

Minor UX concern: In the /usage output, input and output remain cumulative counters while total now reflects totalTokens (context window). In a high-turn session (e.g. inputTokens: 647k, totalTokens: 173k) the display will show "Input: 647.6k / Total: 173k", where Total is smaller than Input alone. Renaming the label (e.g. to "Context window") or separating the cumulative total from the context-window value would eliminate the confusion.

Confidence Score: 4/5

• Safe to merge; the core logic fix is correct and well-tested, with only a minor label-consistency concern in the /usage output.
• The fundamental fix (switching from cumulative inputTokens to context-window totalTokens) is straightforward and correct. Three new browser tests and thirteen node tests cover the key scenarios including the divergent-token regression case. The one style concern is that the "Total" label in /usage can read as less than "Input" in high-turn sessions, which is confusing but not a functional error. No breaking changes to existing interfaces are introduced.
• ui/src/ui/chat/slash-command-executor.ts lines 720–724 — the "Total" display label ambiguity noted above.

This is a comment left during a code review.
Path: ui/src/ui/chat/slash-command-executor.ts
Line: 720-724

Comment:
**`total` label is misleading when `totalTokens` < `inputTokens`**

After this fix, the `/usage` output can display a confusing result like:

```
Input: 647.6k tokens   ← cumulative across all API calls
Output: 50k tokens
Total: 173k tokens     ← current context window (less than Input!)
Context: 87% of 200k
```

`input` and `output` are still cumulative values while `total` now reflects the current context window size. When they diverge significantly (the exact bug scenario this PR fixes), the "Total" line will be smaller than "Input" alone, which is unintuitive. Consider either:
- Renaming the label to something like "Context Window" or "Context Used" to distinguish it from a cumulative total, or
- Using `session.inputTokens + session.outputTokens` for the "Total" display line and keeping `totalTokens` only for the `pct` context percentage calculation.

```suggestion
    const input = session.inputTokens ?? 0;
    const output = session.outputTokens ?? 0;
    const total = session.totalTokens ?? input + output;
    const ctx = session.contextTokens ?? 0;
    const pct = ctx > 0 ? Math.round((total / ctx) * 100) : null;
```

How can I resolve this? If you propose a fix, please make it concise.

_{Last reviewed commit: 9e9b673}

Closing this as implemented after Codex review.

Current main already implements the token-usage fix this PR proposes, with targeted regression tests for both the chat context notice and /usage. The open PR is superseded by code now present on main and by the later cross-referenced PR activity.

What I checked:

• Chat context notice now uses current context snapshot: getContextNoticeViewModel reads session.totalTokens and session.contextTokens, and explicitly suppresses stale snapshots via totalTokensFresh === false, so the notice is based on current context usage rather than cumulative input tokens. (ui/src/ui/chat/context-notice.ts:64, 0bef73d151bd)
• Regression test covers the inflated-token scenario: The test sets inputTokens: 757_300, totalTokens: 190_000, contextTokens: 200_000 and asserts the UI shows 95% context used, 190k / 200k, and does not show 757.3k / 200k. (ui/src/ui/chat/context-notice.test.ts:32, 0bef73d151bd)
• Chat view renders the shared context notice helper: The active chat view calls renderContextNotice(activeSession, ...), so the corrected total-token logic is wired into the actual Control UI chat surface. (ui/src/ui/views/chat.ts:1215, 0bef73d151bd)
• /usage now computes context from totalTokens while preserving cumulative total display: executeUsage keeps Total as cumulative input + output, but computes Context percentage from session.totalTokens when fresh. That matches the bug report and also addresses the prior review note that a Total label based on totalTokens could become misleading. (ui/src/ui/chat/slash-command-executor.ts:380, 0bef73d151bd)
• Node test locks the /usage behavior when cumulative and current-context totals differ: The test case with inputTokens: 1200, outputTokens: 300, totalTokens: 1250, contextTokens: 4000 expects Total: 1.5k and Context: 31% of 4k, proving current main intentionally distinguishes cumulative totals from current context usage. (ui/src/ui/chat/slash-command-executor.node.test.ts:528, 0bef73d151bd)
• PR timeline shows a later landed replacement: The provided GitHub timeline for this PR includes a cross-reference to closed PR fix(ui): use current context usage in Control UI #71462, titled fix(ui): use current context usage in Control UI, on 2026-04-25.

So I’m closing this as already implemented rather than keeping a duplicate issue open.

Review notes: reviewed against 0bef73d151bd.