feat: add v3 native write endpoint support

[philjb]

Adds options to use the v3 native write endpoint for advanced control of write behavior such as the no-sync and accept-partial options. Updates token and auth handling to support v3 alongside v2.

• closes update inch to support influxdb v3 core and enterprise "native" write endpoint #46
• replaces feat: update inch options and url to support influxdb 3 core and improve batch production #47

[Copilot]

Pull request overview

Adds support for InfluxDB v3’s native /api/v3/write_lp endpoint so users can control v3-specific write semantics (e.g., no_sync, accept_partial) while keeping token/auth handling compatible with existing v2 behavior.

Changes:

• Add v3 configuration flags (V3, V3NoSync, V3AcceptPartial) and surface them in CLI parsing.
• Update auth/token handling to apply to both v2 and v3 modes.
• Route writes to the v3 native write endpoint when -v3 is enabled.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
inch.go	Adds v3 options, updates token handling, and switches write URL to v3 native endpoint when enabled.
cmd/inch/main.go	Exposes v3 flags and updates token flag description for v2/v3 usage.

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[Copilot]

In the missing-token case, this returns err from Validate(), which is nil here, so Run() exits successfully (exit code 0) even though an error was printed. Return a real error (and consider writing the message to Stderr) so callers can detect the failure.

Suggested change

	fmt.Println("ERROR: Need to provide a token in order to write into InfluxDB 2 or 3")
	return err
	fmt.Fprintln(os.Stderr, "ERROR: Need to provide a token in order to write into InfluxDB 2 or 3")
	return errors.New("need to provide a token in order to write into InfluxDB 2 or 3")

[Copilot]

This prints the full authorization token to stdout, which is likely to end up in CI logs / shell history and leak credentials. Consider printing only whether a token is set (or a redacted form) and/or gating token output behind -v.

Suggested change

	fmt.Fprintf(s.Stdout, "InfluxDB 2 or 3 Authorization Token: %s\n", s.Token)
	if s.Token == "" {
	fmt.Fprintf(s.Stdout, "InfluxDB 2 or 3 Authorization Token: (not set)\n")
	} else {
	fmt.Fprintf(s.Stdout, "InfluxDB 2 or 3 Authorization Token: (set, length %d)\n", len(s.Token))
	}

[Copilot]

Validate() doesn’t currently enforce any constraints around the new v3 flags beyond a warning. Consider making these cases hard errors: (1) -v2 and -v3 both set (ambiguous behavior), and (2) -v3 set with an empty Database (required for /api/v3/write_lp). This will fail fast instead of producing confusing runtime errors.

Suggested change

	// Enforce mutually exclusive v2/v3 modes.
	if s.V2 && s.V3 {
	el = append(el, errors.New("invalid configuration: cannot enable both v2 and v3 write endpoints; please select exactly one"))
	}
	// Enforce required database when using the v3 write endpoint.
	if s.V3 && strings.TrimSpace(s.Database) == "" {
	el = append(el, errors.New("invalid configuration: database must be set when using the v3 write endpoint"))
	}

[Copilot]

The v3 write URL is built via string formatting without URL-escaping query parameter values. If Database/Precision contain characters that need escaping, the request can be malformed. Use net/url to build the URL + query (and reuse it for the non-v3 branches for consistency).