fix(preview): explain invalid URLs and locators#23396

merged6

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fix/issue-22402

View on GitHubTwo-way sync enabledPR last imported 18h ago

Problem

preview_open({"url":"about:blank","open":false}) returns an internal parse detail without explaining accepted URLs or blank-tab recovery. Invalid preview_click locators and CSS selectors report only the rejected field and its length.

Change

Add accepted URL forms and scope blank-tab recovery to creating a new tab with preview_open. Add locator and CSS-selector guidance to the existing validation errors. Keep normalization, validation, error tags, and wire fields unchanged.

Scope and approval

Fixes #22402 GitCafe: https://git.cafe/pingdotgg/t3code/issues/22402 Triaged bug via the automated issue flow. This corrects existing validation diagnostics without changing accepted inputs or tool capabilities.

Verification

Red: f33cc8a2e8 adds three regression tests that fail on the old messages: missing blank-tab/URL rules, missing locator rules, and missing CSS-selector guidance.
Red execution log: package-local runs at the test-only commit exit 1 with the three expected guidance assertions.
Green on f2a644f07b: node_modules/.bin/vp test run packages/shared/src/preview.test.ts packages/contracts/src/preview.test.ts apps/server/src/mcp/PreviewAutomationBroker.test.ts — 53 tests pass.
Green execution log. Targeted lint passes. Contracts and shared typechecks pass.
Real isolated Linux dev servers compared 8acbefefc5 with f6e8762257, through HTTP MCP and authenticated app WebSocket RPC. Final runtime report; baseline report and commands.

Evidence	Before	After
Invalid URL, omitted-URL blank tab, invalid locator, invalid CSS selector, navigate error, app RPC error, synthetic-input error payloads	8acbefefc5 transcript	f6e8762257 transcript

The final URL guidance qualifies blank-tab recovery with “when creating a new tab,” matching the existing behavior when a tab is reused. Both focused test files pass after that qualification (29 tests), and targeted lint passes.

Before, errors contain only parse/length details. After, errors include recovery guidance; omitted URL opens a blank tab when creating a new tab. Synthetic markers are absent from the returned error envelopes. Visual matrix: empty; this changes protocol error text without a rendered UI change.

Unverified: macOS desktop (cannot-verify desktop). The original valid CSS locator times out on the Linux server browser on both revisions; malformed locator and selector inputs exercise the changed rejection messages. No mobile or Electron shell behavior changed.

Models: Claude Opus 5.5 through Claude Code; GPT-6.1-Sol through the Codex harness.

Takeover

Credit to @juliusmarminge for the original fix. No code changes; evidence and verification added below. Existing final-head rejection captures were retained. Supplemental runtime proof verifies the documented recovery paths at f6e8762257.

Evidence

Independent fixture matrix and provenance. Server protocol recordings are timestamped request/response transcripts; visual matrix has zero rows.

Row	Runtime fixture	Proof / result
U1	Invalid URL through HTTP MCP	Existing before/after: qualified URL recovery guidance
U2	Omitted URL creating a new tab	Existing before/after: owned blank tab
U3	Invalid URL through authenticated app RPC	Existing before/after: unchanged fields/tag, qualified diagnostic
L1	Malformed locator	Existing before/after: latest ref, role/text, CSS guidance
S1	Malformed CSS selector	Existing before/after: CSS and locator guidance
N1	Invalid navigation URL	Existing before/after: qualified URL guidance
P1	Synthetic malformed URL/locator/selector markers	Existing before/after: absent from returned error envelopes
T1	Unmatched valid CSS on blank page	Existing before/after: unchanged timeout
M1	HTTP URL to populated local fixture	Supplemental final-head recording: loaded title/counters
M2	Schemeless URL to same fixture	Supplemental: normalized HTTP URL and loaded title
M3	Omit URL when reusing nonblank tab	Supplemental: same tab, URL and title, including default reuse
M4	CSS selector click	Supplemental: only CSS counter increments
M5	Fresh snapshot ref click	Supplemental: immediate ref use, ref counter increments
M6	Role and text locator clicks	Supplemental: both increment; all four final counters equal 1
D1	Original macOS desktop issue variant	Unverified; no macOS session on this Linux VM

Before: 8acbefefc5 transcript. Relevant paths are identical to recorded PR base 3b95e7831b, as checked by the auditor. After: f6e8762257 rejection transcript, supplemental recovery recording, capture report, reproducible scripts and fixture bundle.

Environment: Linux x64, actual isolated app dev server, authenticated HTTP MCP and app WebSocket RPC, server-browser runtime, deterministic loopback HTML. No rendered UI changed; viewport/theme/font/pixel diffs do not apply. External fixture scripts are uploaded rather than committed under the evidence-only/no-code-change constraint. What else changed: only diagnostic text in the PR diff; no accepted inputs, defaults, tool capabilities, wire fields or rendered UI changed. Supplemental interactions exercise existing recovery behavior.

Verification log

Final head: f6e8762257; source unchanged; no branch merge, push or claim comment.
Independent proof passes: matrix derivation, then final transcript audit and one affected runtime reproduction. Final independent audit: SUFFICIENT. The reproduced locator-error envelope exactly matches the supplied final-head capture.
Focused tests: 53 passed across shared preview, contracts preview and server PreviewAutomationBroker at the final head. Execution log. Tests unchanged.
Final-head CI snapshot at publication: 34 successful, 0 pending, 0 failing. Existing bot feedback was read; no code review/implementation rounds were performed in evidence-only mode.
Unverified: original macOS desktop reproduction (D1). No mobile or Electron shell behavior changed. No unverified affected server row remains.
No merges. Owned runtime processes stopped; lead removes isolated worktree and scratch after publication.
Model: GPT-6.1-Sol through Codex for capture and independent proof audit.

Checks

22 successful · 17 skipped

All checks passed

Added 3 commits12d ago

fix(preview): invalid URL and locator errors say what to send instead4b02a6b
test(preview): require actionable invalid URL and locator errors66748d1
fix(preview): scope blank-tab hint in URL errors to preview_openf2a644f

MmacroscopeappBotapproved these changes · review dismissed12d ago

MmacroscopeappBot12d ago

Approvability

Verdict: Approved at b6f3742

Macroscope's review found this PR approvable — Improves preview URL and locator errors with actionable usage guidance, including the new-tab qualification. Validation and tab defaults remain unchanged, so the change carries no material operational risk.

Notes:

All code in this push has already been reviewed. Approvability was decided on eligibility alone.

No code changes detected at b0c25aa. Prior analysis still applies.

^{You can add or adjust custom eligibility rules. Learn more.}

Ggithub-actionsBot12d ago

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	+19 B (+0.4%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.3 KiB	+19 B (+1.5%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	21.6 KiB	21.6 KiB	0 B (0.0%)	24.4 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.1 KiB	+17 B (+0.3%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.3 KiB	+17 B (+1.3%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.9 KiB	21.9 KiB	0 B (0.0%)	24.4 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: f6503f0 · PR result: b0c25aa · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

Codex decoded thread snapshot: 108.5 KiB
Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

CcoderabbitaiBot12d ago

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Walkthrough

Preview URL and selector validation errors now explain accepted input forms and alternatives. Tests check the added URL and selector guidance.

Changes: Preview validation guidance

Layer / File(s)	Summary
URL error guidance `packages/contracts/src/preview.ts`, `packages/shared/src/preview.ts`, `packages/shared/src/preview.test.ts`	URL errors describe accepted HTTP(S) URLs or schemeless hosts and explain how to request a blank tab. A test checks the normalization error message.
Selector error guidance `packages/contracts/src/previewAutomation.ts`, `packages/contracts/src/preview.test.ts`	Locator errors describe supported locator forms and direct CSS to `selector`. Selector errors clarify that `selector` takes CSS and `locator` takes refs, roles, or text. Tests check both message types.

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix · Severity of issue fixed: Low

Possibly related issues

pingdotgg/t3code#25641 — The URL error now includes a blank-tab hint when about:blank remains unsupported; URL acceptance and normalization are unchanged.

Suggested reviewers: maria-rcks, t3dotgg

Merge Risk: External image Minimal · previous review b6f37

No actionable merge-blocking risk is established; the PR is mergeable.

Pre-merge checks: ^Passed 4

Check name	Status	Explanation
Title check	Passed	The title clearly and concisely describes the main change: improved diagnostics for invalid preview URLs and locators.
Description check	Passed	The description includes the required Problem, Change, Scope and approval, and Verification sections. It explains the affected behavior, linked issue, scope, tests, runtime checks, limitations, and ag…
Linked Issues check	Passed	Issue `#22402` requires actionable validation guidance for URL, locator, and CSS-selector inputs. The diff adds HTTP(S) and schemeless-host guidance and states that omitting `url` creates a blank tab wh…
Out of Scope Changes check	Passed	The diff changes only preview diagnostic messages and adds focused regression tests for those messages. The changes preserve the existing error details and selector branches. No unrelated capability, …

Full details: Description check

Explanation

The description includes the required Problem, Change, Scope and approval, and Verification sections. It explains the affected behavior, linked issue, scope, tests, runtime checks, limitations, and agent details.

Full details: Linked Issues check

Explanation

Issue #22402 requires actionable validation guidance for URL, locator, and CSS-selector inputs. The diff adds HTTP(S) and schemeless-host guidance and states that omitting url creates a blank tab when creating a new tab. It states that locators accept aria-ref=<ref> and Playwright role/text selectors, and that CSS belongs in selector. Tests cover the URL, locator, and CSS-selector messages. The multiple-tab error-tag observation has no concrete coding acceptance requirement.

Full details: Out of Scope Changes check

Explanation

The diff changes only preview diagnostic messages and adds focused regression tests for those messages. The changes preserve the existing error details and selector branches. No unrelated capability, accepted input, wire field, normalization behavior, or rendered UI change is present.

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CcoderabbitaiBotreviewed · 1 inline thread12d ago

Actionable comments posted: 1

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6	Inline comments:
7	Review comments at @packages/shared/src/preview.ts:
8	- Line 69: Update the invalid-preview-URL guidance in PreviewInvalidUrlError to
9	clarify that omitting url opens a blank tab only when creating a new tab;
10	preserve the existing guidance for other preview_open behavior.
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packages/contracts/src/preview.test.ts
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packages/shared/src/preview.tsline 69Outdated · f2a644fResolved by Julius Marminge

Added 1 commit12d ago

fix(preview): qualify blank-tab guidance for new tabsf6e8762

MmacroscopeappBotapproved these changes · review dismissed12d ago

packages/shared/src/preview.tsline 69Outdated · f6e8762Open thread

…	…	@@ -66,7 +66,7 @@ export class PreviewUrlNormalizationError extends Schema.TaggedError<PreviewUrlN
67	67		override get message(): string {
68	68		const protocol = this.protocol === undefined ? "" : `: ${this.protocol}`;
69		-	return `Invalid preview URL (${this.reason}${protocol}; input length ${this.inputLength}).`;
	69	+	return `Invalid preview URL (${this.reason}${protocol}; input length ${this.inputLength}). Use an http(s) URL or a schemeless host such as localhost:5173. With preview_open, omit url when creating a new tab to open a blank tab.`;

JJulius Marmingeon line 6912d ago

Confirmed: preview_open defaults to reusing the selected tab and leaves its page unchanged when url is omitted. f6e8762257 qualifies both URL error messages with “when creating a new tab” and strengthens the existing assertion. Both focused files pass (29 tests); targeted lint passes.

JJulius Marmingereviewed12d ago

Added 1 commit4d ago

Merge remote-tracking branch 'origin/main' into HEADb6f3742

MmacroscopeappBotapproved these changes4d ago

Added 1 commit21h ago

Merge branch 'main' into fix/issue-22402b0c25aa