What causes "invalid format template: %w" in gastownhall/beads?

Fix the template syntax per the wrapped parse error's line/column

invalid format template: %w

Error message

invalid format template: %w

What it means

outputFormattedList parses the --format string as a Go text/template; this error wraps the template.Parse failure. It means the user-supplied format string has invalid template syntax. The underlying parse error (line/offset) is wrapped via %w.

Source

Thrown at cmd/bd/list_output.go:119

		return outputDotFormat(out, issues, depsByIssueID)
	}
	w := &graphExportWriter{out: out}

	// Built-in format presets
	presets := map[string]string{
		"digraph": "{{.IssueID}} {{.DependsOnID}}",
	}

	// Check if it's a preset
	templateStr, isPreset := presets[formatStr]
	if !isPreset {
		templateStr = formatStr
	}

	// Parse template
	tmpl, err := template.New("format").Parse(templateStr)
	if err != nil {
		return fmt.Errorf("invalid format template: %w", err)
	}

	// Build map of all issues for quick lookup
	issueMap := make(map[string]bool)
	for _, issue := range issues {
		issueMap[issue.ID] = true
	}

	// For each issue, output its dependencies using the template
	for _, issue := range issues {
		for _, dep := range depsByIssueID[issue.ID] {
			// Only output edges where both nodes are in the filtered list
			if issueMap[dep.DependsOnID] {
				// Template data includes both issue and dependency info
				data := map[string]interface{}{
					"IssueID":     issue.ID,
					"DependsOnID": dep.DependsOnID,
					"Type":        dep.Type,

View on GitHub (pinned to 71377f2769)

Solutions

Fix the template syntax per the wrapped parse error's line/column
Use double quotes in your shell so braces aren't mangled: --format '{{.ID}} {{.Title}}'
Check field names match Issue struct fields (e.g. {{.Issue.Title}} in dependency context)
Test with a minimal template like '{{.ID}}' first

Example fix

// before
bd list --format '{{.ID' 
// after
bd list --format '{{.ID}} {{.Title}}'

Defensive patterns

Strategy: validation

Validate before calling

# Sanity-check braces balance before invoking
tpl='{{.ID}} {{.Title}}'
[[ $(grep -o '{{' <<<"$tpl" | wc -l) -eq $(grep -o '}}' <<<"$tpl" | wc -l) ]] || { echo "unbalanced template braces"; exit 2; }
bd list --format "$tpl"

Try / catch

// Catch and surface the wrapped parse error (position info)
out=$(bd list --format "$tpl" 2>&1) || case "$out" in
  *"invalid format template"*) echo "$out" >&2; exit 1;; esac

Prevention

Start from a known-good template like '{{.ID}} {{.Title}}'
Single-quote templates in shell to protect braces and %
Keep Go text/template syntax docs handy; Go template != Jinja

When it happens

Trigger: `bd list --format '{{.ID'` or any --format value with unbalanced braces, bad actions, or invalid functions passed to template.New("format").Parse.

Common situations: Hand-written format strings with typos (`{{.id}` — wrong case or missing brace), shell interpolation mangling braces, copying templates from docs for other tools.

Related errors

AI-assisted analysis of gastownhall/beads@71377f2769 (2026-08-30). Data as JSON: /api/errors/2e45c1dcee6f4f79. Report an issue: GitHub.