The usage page's Server-Timing names its phases: session, each read, render #4182

/settings/usage now answers with a Server-Timing header naming session, patterns, usage and render. I merged current main (release 0.7.227) into the branch and pushed it. The type check is clean. test/usage-timing.test.ts and test/server-timing-sweep.test.ts pass (5 tests). I did not run the full suite, which the forge's check does.

• Phases: the page uses notePhase and timePhase from src/core/route_timing.ts, as boards-view.ts does. patterns times the list of known route patterns, usage times routeUsage, and render times building the page.
• Order and errors: the two reads run in their original order and any error from either still propagates.
• Unchanged: the page body, status codes and caching are the same, and nothing is computed just for the header.
• Tests: test/usage-timing.test.ts requests the page and asserts each phase name appears with a duration. I did not run it against the old code to confirm it fails there. I also took /settings/usage off the debt list in test/server-timing-sweep.test.ts.

To try it, request /settings/usage while signed in and read the Server-Timing response header.

I left the Server-Timing header off the other settings pages.

Closes #3279

/settings/usage now answers with a Server-Timing header naming session, patterns, usage and render. I merged current main (release 0.7.227) into the branch and pushed it. The type check is clean. test/usage-timing.test.ts and test/server-timing-sweep.test.ts pass (5 tests). I did not run the full suite, which the forge's check does.

• Phases: the page uses notePhase and timePhase from src/core/route_timing.ts, as boards-view.ts does. patterns times the list of known route patterns, usage times routeUsage, and render times building the page.
• Order and errors: the two reads run in their original order and any error from either still propagates.
• Unchanged: the page body, status codes and caching are the same, and nothing is computed just for the header.
• Tests: test/usage-timing.test.ts requests the page and asserts each phase name appears with a duration. I did not run it against the old code to confirm it fails there. I also took /settings/usage off the debt list in test/server-timing-sweep.test.ts.

To try it, request /settings/usage while signed in and read the Server-Timing response header.

I left the Server-Timing header off the other settings pages.

I merged current main into the branch, resolved the one conflict, and pushed.

The conflict was in the list of pages still missing a Server-Timing header in test/server-timing-sweep.test.ts. main had dropped /signin and /signup from that list. This branch had dropped /settings/usage, which it now instruments. I kept both removals, so /signin, /signup and /settings/usage are all off the list.

test/usage-timing.test.ts and test/server-timing-sweep.test.ts pass (5 tests), and the type check is clean. I did not run the full suite, which the forge's check does.