Take out-of-band MCP directives out of connect screens - #165
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WalkthroughThe Telnet crawler updates ChangesMCP Telnet support
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to This PR removes out-of-band directives from stored connect screens while preserving ordinary screen text and recording MCP capability; no actionable merge-blocking risk remains beyond normal checks and review. Sequence Diagram(s)sequenceDiagram
participant ProbeSession
participant TelnetProbe
participant MudClientProtocol
participant Negotiation
participant FieldObservations
ProbeSession->>TelnetProbe: process Telnet session data
TelnetProbe->>MudClientProtocol: register MCP handling
MudClientProtocol-->>TelnetProbe: detect offer and package names
TelnetProbe->>Negotiation: store MCP capability and packages
Negotiation->>FieldObservations: provide package list
FieldObservations-->>ProbeSession: emit handshake observation
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches📝 Generate docstrings
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Inline comments:
In `@tests/MUI.Crawl.Tests/Telnet/ProbeSessionTests.cs`:
- Line 1688: Add MCP capability detection coverage for the unquoted MCP offer in
the relevant ProbeSession test, either by asserting MCP in the existing unquoted
test or by adding a dedicated unquoted capability test; retain the quoted-syntax
coverage.
- Line 1675: Strengthen the directive-removal assertions in both tests: at
tests/MUI.Crawl.Tests/Telnet/ProbeSessionTests.cs lines 1675-1675, verify mcp
version: is absent or the complete expected banner matches; at lines 1739-1739,
verify SDWC-START-NOWRAP, LOGIN_TRIGGER, and SDWC-END-NOWRAP are all absent from
the banner.
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Directory.Packages.propssrc/MUI.Crawl/Telnet/TelnetProbe.cstests/MUI.Crawl.Tests/Telnet/ProbeSessionTests.cs
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HarryCordewener
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AnExpiredTokenDoesNotCompleteAClaim has been failing on main since some time on 2026-08-31, with nothing changed to cause it. The date caused it. ExpireAsync wrote `expires_at = now() - interval '1 day'` -- the database's wall clock -- while the query it is setting up compares expires_at against the injected clock. The two agreed only while real time stayed behind the seeded clock plus the lifetime under test, and that window closed on its own: Seed.Now 2026-07-30 12:00Z + PendingLifetime + 1 day 2026-08-30 12:00Z <- what the query compares now() - 1 day 2026-08-30 15:25Z <- what the row said Once the real calendar passed 2026-08-31 12:00Z the row stopped being in the past as far as the query was concerned, so an expired token began reading as Verified. The last green run on main was 2026-08-29. The clock is injected precisely so that "later" is a fact rather than a sleep; reaching for now() in the middle of that gave the test a dependency on the day it happened to run. It now expires relative to the clock the query uses, which is deterministic by construction. Found while opening #165, whose CI this was failing. Unrelated to that change -- it reproduces on unmodified main. 641 MUI.Catalog.Tests green. Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
BLOCKED until TelnetNegotiationCore 2.13.0 is published: this pins it, and that version does not exist on nuget.org yet. It is HarryCordewener/TelnetNegotiationCore#92. Measured against the catalogue, not supposed. 56 of the 918 stored connect screens carry a line beginning #$#, and 54 of those lines are a MOO's MCP offer: 37 #$#mcp version: 2.1 to: 2.1 (unquoted) 17 #$#mcp version: "2.1" to: "2.1" Every one of them was being stored and shown as though it were part of the screen. Registering MudClientProtocol takes them out of the stream, and the offer is recorded as an observed capability -- the offer arriving is the whole of the evidence that a server speaks MCP. Deliberately WITHOUT answering. The crawler has no use for an MCP session, and answering would put text on a stranger's login prompt for one it will never open -- the objection MSSPPlaintextProtocol makes to sending MSSP-REQUEST unbidden, though weaker here because the server did ask. The offer is consumed either way; only the reply is suppressed. No session opens, so a later #$# line is still treated as ordinary output, which is the conservative reading and the one that keeps ASCII art safe. That last point is not hypothetical: 3 of the 59 screens matching #$# anywhere match only mid-line, inside art -- "d######## #$#", "'##$#" -- and a substring strip would eat the artwork off them. A test pins it. The remaining 3 line-initial matches are not MCP and are untouched: two "#$# SDWC-*-NOWRAP" and one "#$#LOGIN_TRIGGER". Stored screens keep the pollution until re-crawled. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
TelnetNegotiationCore's framing now follows the specification rather than a stricter reading of it: a line-initial #$# that cannot be acted on is dropped rather than passed through, in a session or outside one. MCP says so plainly -- an unrecognised message on that prefix is silently dropped, not shown to a reader. For the crawler that means the other three lines go too. All 57 line-initial #$# lines in the catalogue now come out of the screen, not just the 54 MCP offers: also two "#$# SDWC-*-NOWRAP" and one "#$#LOGIN_TRIGGER", which are somebody's client directives sent on the prefix reserved for exactly that, and which no reader should have been shown either. Line-initial is still what keeps ASCII art safe, and the catalogue is the evidence: of the 59 screens matching #$# anywhere, the 3 that match only mid-line are all art. Both cases have a test. 555 tests green. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Both review findings, and both fair. The removal tests asserted only that "#$#" was absent, which a regression that stripped the marker and left "mcp version: 2.1 to: 2.1" in the screen would have passed. They now name what must be gone -- the message text, and each of SDWC-START-NOWRAP, SDWC-END-NOWRAP and LOGIN_TRIGGER -- and assert the exact banner that should remain, which is the strongest form available here. Capability detection was only covered for the quoted spelling of the offer, while the unquoted one is what 37 of the 54 real offers in the catalogue actually use. The unquoted test now asserts it too. 65 ProbeSessionTests green. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Measured first, on the 14 live catalogue games that offer MCP: every one answers a reply with its whole mcp-negotiate-can list, before login and without an account. That list is a capability fingerprint no other probe yields, and a codebase tell besides -- org-fuzzball-* names Fuzzball as surely as a version banner does. 9/9 org-fuzzball-gui 9/9 org-fuzzball-notify 9/9 dns-org-mud-moo-simpleedit 8/9 org-fuzzball-help 9/9 org-fuzzball-simpleedit 9/9 mcp-negotiate and, on richer servers, dns-com-awns-ping, dns-com-awns-status, dns-com-zuggsoft-msp, org-fuzzball-loadimage, -dump, -languages, -chess and -extern. The previous change declined to answer, on the grounds that it would put text on a stranger's login prompt. That argument was weaker than it looked and is withdrawn: this probe already types WHO, INFO and VERSION at the same prompt, unbidden, and the MCP answer is one line that the server invited. TheCrawlerAnswersAnMcpOfferExactlyOnce holds it to that -- one reply, and no packages advertised beyond the one mcp-negotiate is required to name for itself. Read from PeerPackages rather than Agreed: the crawler declares no packages of its own, so an agreed set would be empty and the interesting half thrown away. Read off the plugin at snapshot time rather than through a callback, because a server that offers MCP and lists nothing is a fact worth keeping too, and no callback fires for it. Stored through FieldObservations rather than upserted like the connect screen: a package list is stable, so a game gaining or losing one is a genuine event that deserves its change-feed row. Emitted before the charset early-return, or a server that never settled CHARSET would lose its list to an unrelated yield break. Verified end to end against vore.got-game.org:8888 with the real probe and the published 2.13.0 -- 10 packages, and worth noting that the same probe prints "codebase — nothing the reader would stand behind" while the package list says Fuzzball plainly. Inferring the codebase from it is a follow-up, not this change. 557 MUI.Crawl.Tests and 340 MUI.Crawler.Tests green; solution builds clean. Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
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A MOO's connect screen opens with its MCP offer, and we have been storing and showing that line as
though it were part of the screen.
Measured against the catalogue, not supposed. Of the 918 stored connect screens, 56 carry a line
beginning
#$#, and 54 of those lines are the offer:#$#mcp version: 2.1 to: 2.1— unquoted, the majority spelling#$#mcp version: "2.1" to: "2.1"#$# SDWC-START/END-NOWRAP#$#LOGIN_TRIGGERAll 57 come out. The three that are not MCP are somebody's client directives sent on the prefix
reserved for exactly that, which no reader should have been shown either.
The change
Deliberately without answering. The crawler has no use for an MCP session, and answering would put
text on a stranger's login prompt for one it will never open — the objection
MSSPPlaintextProtocolmakes to sending
MSSP-REQUESTunbidden, though weaker here because the server did ask first. Only thereply is suppressed: the inbound framing is not conditional on a session, so every line-initial
#$#comes out regardless.
The offer is also recorded as a capability. There is no negotiation to observe, so the offer
arriving is the whole of the evidence that a server speaks MCP — which is why
TelnetNegotiationCoregrewOnMcpOfferedrather than making us open a session to learn it.Line-initial is what keeps ASCII art safe
Of the 59 screens matching
#$#anywhere, the 3 that match only mid-line are all art —d######## #$#,'##$#. A substring strip would eat the artwork off them. Both cases have a test.Notes
which was true when it was written and is not any more.
FakeGame: the offer leaves the banner, the rest of the screensurvives, MCP is recorded, the crawler sends nothing back, and mid-line
#$#is untouched.555
MUI.Crawl.Testsgreen against the published 2.13.0; full solution builds with 0 warnings.🤖 Generated with Claude Code
Summary by CodeRabbit
New Features
Bug Fixes