Improve ASCII chart rendering

[flash1293]

Multi-metric bar charts
Braille-based horizontal area charts

[github-actions]

tl;dr: The highest-confidence fix is to unify chart rendering between tool output and TUI (currently different width logic), then add an explicit ASCII fallback mode; this directly targets rendering quality and avoids mode-dependent chart shape differences.

Recommendation

Implement a single shared chart renderer in packages/opencode/src/tool/chart.ts that accepts a width parameter and rendering charset mode (unicode/ascii), and have both CLI run output and TUI use it.

Findings

Code evidence

1. Tool output uses fixed-width bars and Unicode blocks:

// packages/opencode/src/tool/chart.ts:5
export const BAR_WIDTH = 20

// packages/opencode/src/tool/chart.ts:10
export function render(value: number, max: number, color?: string): string {

2. Headless run path prints tool output directly:

// packages/opencode/src/cli/cmd/run.ts:74
const output = info.part.state.output

3. TUI re-renders the same chart metadata with dynamic widths and its own bar renderer:

// packages/opencode/src/cli/cmd/tui/routes/session/index.tsx:1674
barW = Math.max(1, Math.min(100, room))

// packages/opencode/src/cli/cmd/tui/routes/session/index.tsx:1679
barW = Math.max(1, Math.min(50, room))

// packages/opencode/src/cli/cmd/tui/routes/session/index.tsx:1714
function renderBarDyn(value: number, max: number, width: number) {

4. Local history shows chart renderer landed in commit 9fe0c4c; tests focus on Unicode/ANSI integrity, not ASCII fallback behavior.

Verification

Commands and output

$ cd packages/opencode && bun test test/tool/chart.test.ts
bash: bun: command not found

$ node -e '/* render math repro */'
RangeError: Invalid count value: -1

$ grep -nE "BAR_WIDTH = 20|function render\(|output: body.join|part.state.output" \
  packages/opencode/src/tool/chart.ts packages/opencode/src/cli/cmd/run.ts
packages/opencode/src/tool/chart.ts:5:export const BAR_WIDTH = 20
packages/opencode/src/tool/chart.ts:10:export function render(value: number, max: number, color?: string): string {
packages/opencode/src/tool/chart.ts:202:      output: body.join("\n"),
packages/opencode/src/cli/cmd/run.ts:74:  const output = info.part.state.output

$ grep -nE "barW = Math.max|renderBarDyn" packages/opencode/src/cli/cmd/tui/routes/session/index.tsx
1674:      barW = Math.max(1, Math.min(100, room))
1679:      barW = Math.max(1, Math.min(50, room))
1714:  function renderBarDyn(value: number, max: number, width: number) {

Detailed Action Plan

Implementation steps

1. In packages/opencode/src/tool/chart.ts, extract a shared primitive that renders bars with configurable width and charset (unicode blocks vs ASCII fallback symbols).
2. Refactor current tool path (barChart/render) to call that shared primitive instead of fixed BAR_WIDTH internals only.
3. In packages/opencode/src/cli/cmd/tui/routes/session/index.tsx (chart component around 1648-1870), replace duplicated renderBarDyn math with calls to shared chart-render helpers so TUI and tool output use identical scaling/rounding logic.
4. Keep TUI width adaptation (barW) but pass width into shared renderer; ensure metadata-driven rendering produces equivalent proportions across TUI/headless modes.
5. Add explicit ASCII fallback option in chart metadata/output (for environments where Unicode block/box drawing is undesirable) and map borders/bars accordingly.
6. Extend packages/opencode/test/tool/chart.test.ts with:
   • parity tests for configurable width,
   • ASCII fallback snapshots/shape assertions,
   • negative/mixed-sign safety coverage (no throw, fixed-width output).

Related Items

Links and references

Type	Link / Path	Relevance
Issue	#81	Current triage target
Commit	9fe0c4c	Introduced current chart implementation/tests baseline
File	packages/opencode/src/tool/chart.ts	Core chart rendering implementation
File	packages/opencode/src/cli/cmd/tui/routes/session/index.tsx	TUI chart re-render path with separate logic
File	packages/opencode/src/cli/cmd/run.ts	Headless output path prints tool-rendered chart
File	packages/opencode/test/tool/chart.test.ts	Existing chart tests to extend

Note: I could not fetch issue/PR discussion history via GitHub MCP in this run because those resources were filtered by integrity policy, so related-item analysis is based on local repository evidence.

Note

🔒 Integrity filter blocked 4 items

The following items were blocked because they don't meet the GitHub integrity level.

• #81 issue_read: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #81 search_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• Improve ASCII chart rendering #81 issue_read: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #68 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

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