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Hey HN! I made Orbit, an iOS app that allows you to see the satellites, planets, and constellations above you in AR, on a 2D map, and on a 3D globe. The app includes more than 15,000 objects tracked by CelesTrack, together with their pass predictions, descriptions, and detailed orbital data. A searchable catalog of all objects is also available, as well as a built-in chatbot designed to answer any space-related questions you might have. This is my first published iOS app, so any feedback is grea

If you've ever tried to duplicate a Keycloak realm on the same server — say, to spin up a myrealm-dev realm alongside your existing myrealm — you've probably hit this wall: Export the realm from the Admin Console ( Realm settings → Action → Partial export , with clients and groups/roles included). Rename it in a text editor, or in the import dialog's "realm name" field. Import it back into the same Keycloak instance. Watch it fail with: ERROR: duplicate key value violates unique constraint "constraint_a" Detail: Key (id)=(51e1a26d-c24f-4454-9a34-708f1fc14917) already exists. Why this happens A realm export isn't just configuration — it's a snapshot of database rows. Every role, client, user, protocol mapper, component, and authentication flow in the export carries the same internal UUID it has in the live database. Renaming the realm field changes what the realm is called , but it does nothing to the dozens (often hundreds) of UUIDs referenced throughout the file. Import that JSON into the instance it came from, and Keycloak tries to insert rows whose primary keys already exist. Every single one collides. This is a known limitation, tracked upstream as keycloak/keycloak#24770 . Keycloak's exporter was never designed to produce an import-anywhere-including-here artifact — it assumes you're moving the realm to a different instance (dev → staging → prod), where the UUID space is independent. The manual fix (and why it doesn't scale) In principle you can fix this by hand: open the export JSON, find every UUID, and replace it with a fresh one, while keeping track of which old UUID maps to which new UUID so that references between objects (a role's containerId , a client's serviceAccountClientId , a flow's execution list) still point at the right thing after the rewrite. For a small realm with a handful of clients this is tedious but doable in an editor with careful find-and-replace. For a realm with custom roles, several clients, an identity provider, and a full set of a

Developers flagged a freshly filed, reproducible issue that should make anyone running background agents pause: Claude Code's background Opus subagents intermittently stall on their first turn and, instead of producing useful work, emit system-prompt fragments — including text shaped like authorization data — as their only output. It's labeled a security issue, it has a reproduction, and it's open. That's enough to treat it as a real, if intermittent, class of failure. Here's the mental model that matters: a subagent is not a trusted subprocess. It's an autonomous loop with access to a context window, a toolset, and — too often — the same credentials as its parent. When that loop stalls and dumps its prompt instead of its result, anything that was in context is now in output. Authorization-shaped text leaking is the canary: if the prompt carried a token, a session string, or an internal endpoint, that's what surfaces. The fix is structural, not reactive. Three rules: 1. Scope credentials per subagent, not per session. A background agent that only needs to read a repo shouldn't hold deploy keys. Hand it the narrowest token that completes its task and revoke it when the task ends. If the tooling can't scope credentials, that's a gap to close before you scale subagents. 2. Treat subagent output as untrusted. Anything a subagent returns — including error text, logs, and especially "stalled" dumps — should be parsed and sanitized before it touches shared state. Don't pipe raw subagent output into a context that feeds other agents or into any log that leaves your machine. 3. Separate the system prompt from the working context. The leak happened because authorization-shaped content sat in the same window the subagent could echo. Keep credentials and internal routing data out of the prompt that a stalled loop might surface. Put them in a side channel the model can call, not text it can print. The deeper lesson is about failure modes, not one bug. Most agent setups assume th

The feed showed a new entrant worth watching: Tencent has launched Hy3, a coding-focused AI model, with input tokens priced at $0.14 per million. For developers who live in the terminal running coding agents, that price point lands well below the per-token rates most frontier models charge, and it puts a major lab's coding model into the "cheap enough to leave running" category. What makes this interesting isn't just the number — it's the positioning. Hy3 is being pitched specifically as a coding AI, not a general chatbot, which suggests vendors are starting to carve out developer-facing models with their own pricing tiers rather than forcing coders to pay general-purpose rates. Developers spotted the launch in the daily AI news roundup and immediately started comparing it against the cost of running their existing agents. The catch, as always, is what the headline price doesn't tell you: output token cost, context-window limits, and how the model actually performs on real repository tasks all remain open questions. A low input price is meaningless if output is expensive or if the model needs five retries to get a diff right. Still, a credible cheap coding model from a major player is exactly the kind of pressure that nudges the whole category toward per-token transparency. If nothing else, it gives every other vendor a new number to justify theirs against.

Welcome to Learning Xahau, a series of articles dedicated to helping developers, builders, and blockchain enthusiasts better understand the Xahau ecosystem. Whether you're just getting started or already building advanced applications, these posts will explore Xahau's features, architecture, and best practices through practical examples and real-world use cases. If you've been building with Hooks on Xahau, you know the basic loop: write a C program, compile it to WebAssembly, install it on an account, and it fires automatically when that account is involved in a transaction. Simple and powerful, but until the 2026.6.21 major release, there were some friction points that made real-world hook architectures more complicated than they needed to be. This release ships three improvements that directly address those friction points: HookOnV2 : split the single HookOn bitmask into separate HookOnIncoming and HookOnOutgoing controls NamedHooks : assign a human-readable name to each hook slot, so senders can choose which hook to activate Simulate RPC : preview a transaction including all hook executions without spending fees or changing ledger state None of these require rewriting your hook logic. They are configuration and tooling improvements at the SetHook and transaction level. But they fundamentally change what you can build cleanly. All code in this article targets the Xahau Testnet ( wss://xahau-test.net ) and requires xahau.js 4.1.1 or later. Clone the companion repository: git clone https://github.com/Ekiserrepe/learningxahau20260621.git cd learningxahau20260621 npm install Copy .env.example to .env and fill in the seeds used across these examples: cp .env.example .env HUB_SEED = # account that installs the directional hook (07, 08, 09) NAMED_HUB_SEED= # account that installs and owns the named hooks (10, 11, 13, 14) SENDER_SEED = # account that sends payments targeting a named hook (12, 14) All accounts need testnet funds from the Xahau Testnet Faucet . HookOnV2: Di

Every Java engineer who has connected JConsole — or JDK Mission Control — to a server in another network segment knows the ritual. Open the JMX port. Discover that RMI quietly opened a second port — random by default. Pin it with a system property nobody remembers without searching. File a firewall ticket for both. Wait. What fewer people know: the JMX specification shipped with the second remote transport that has none of these problems. One socket, one port, TLS underneath if you want it. It's called JMXMP — the JMX Messaging Protocol. It lost for the least mysterious reason in software — RMI shipped by default, JMXMP was a separate download, and defaults win — and its reference implementation has been effectively abandoned since around 2008. Yet, it never quite died. Code that refuses to die usually knows something. I didn't set out to resurrect it. I fell into it. The port dance, briefly The default remote JMX stack rides on RMI. The connection URL tells you most of the story: service:jmx:rmi:///jndi/rmi://host:1099/jmxrmi I'll spare you the full anatomy behind that URL — there's a JNDI lookup in it, and that second, dynamically assigned port from the ritual above; few people ever learn the details, which is rather the point. Dynamic ports were a reasonable design for 1999's flat networks. Between today's firewalls, NAT, and containers, they're friction — not because RMI is bad, but because the network it was designed for no longer exists. The JMXMP URL: service:jmx:jmxmp://host:9875 One socket. TCP in, TCP out. That's the whole networking story. How I ended up in this codebase I maintain JConsoleBooster , a modernized JConsole. It shipped fine for years on the 2008-era JMXMP jar — the one historically distributed as jmxremote_optional / jmx-optional , out of Sun's OpenDMK project, republished over the years by several parties because people kept needing single-socket JMX. Then I moved the app to a jlink -built runtime. An automatic module from 2008 does not coo

Save your best ports for your most demanding devices.