feat(inbox): Add slug suffix to inbox report deep links

[Twixes]

Problem

People are sharing PostHog Code inbox links like posthog-code://inbox/01928f7a-… - problem is the link tells you nothing about what's on the other side. When pasted into Slack, a PR, or a doc, the recipient has no signal whether the link is worth clicking.

Changes

Deep links now include a human-readable slug of the report title after the UUID, like Graphite PRs:

posthog-code://inbox/<uuid>/fix-inbox--Add-foo

The slug is cosmetic-only, and slug-less are links are supported as always. (Did not test if slugful links work on older PH Code, likely not).

Slugification rules:

• Accented Latin folded to ASCII (café → cafe) via NFD normalization
• Letters, digits, and URL-unreserved punctuation (_ . ~) kept verbatim, case preserved
• Runs of other characters collapse to a single -, except runs that mix a colon with other unsafe chars collapse to -- (so the title-like break in fix(inbox): Add foo reads as fix-inbox--Add-foo)

Updated the "Copy link" button to use this.

How did you test this?

Very pleasant to unit-test the slugification, it's now in apps/code/src/shared/deeplink.test.ts. Also updated buildDiscussReportPrompt.test.ts. Finally, clicked around manually.

Publish to changelog?

Yes - PostHog Inbox sharing links now include human-readable titles for easy sharing.

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 1
apps/code/src/shared/deeplink.test.ts:7-71
**Prefer parameterised tests**

Several blocks in this file bundle multiple distinct input→output cases into a single `it` (e.g. `null`/`undefined`/`""` in "returns just the UUID when no title is given" at lines 7–15, and `":::"` / `"   "` in "omits the slug when the title slugifies to empty" at lines 32–40). The whole suite is essentially a table of `(title, expectedSlug)` pairs, which is exactly what `it.each` is designed for. A single parameterised block would make adding further cases trivial and give each case its own labelled failure message.

_{Reviews (1): Last reviewed commit: "feat(inbox): add slug suffix to inbox re..." | Re-trigger Greptile}

[adboio]

if the goal is better human-readable, i have two thoughts:

1. can we just remove the UUID entirely? like posthog-code://inbox/fix-inbox--Add-foo - maybe scope it with a short ID for project/user/etc if needed
2. are there plans to have web links for sharing these? e.g. we just added https://posthog.com/code/open yesterday which deeplinks to the app, and falls back to a download msg. maybe we could link to us.posthog.com/inbox/task-slug or something and that'd deeplink to phc, or show the task in web as a fallback, idk ?

[Twixes]

Hmm, I don't think we can drop the UUID. Well, perhaps the thing is a UUID is too verbose here, and a serial ID would in fact be better (words I never thought I'd say). Then, posthog.com/code/open makes perfect sense. I'll actually move the logic there.