mixandClaude Opus 5.5
ad3d834392
Comments only, no behaviour changed. modernc.org/sqlite v1.60.1 (the _pragma list on every connection, busy_timeout first; extended result codes; a deferred BEGIN; multi-statement Exec) and SQLite 3.53.4's documentation (transactions, WAL, foreign keys, NOCASE, upsert, julianday, partial indexes); htmx 2.0.4 src/htmx.js; the Fetch and HTML standards for Sec-Fetch-Site, Origin, SameSite, __Host-, CSP and defer order; Go's html/template. Comments the source contradicts are corrected - the driver does not serialise writes (SetMaxOpenConns(1) does), htmx:load fires per swapped element, no-store does not keep a page out of history. Left for their own commits: D-S3 a migration two processes can both run, D-S20 recipient case, D-B3 Origin: null under Referrer-Policy: no-referrer, D-H5/H6/H7/H9 (audit M11, stage 4). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
71 lines
2.7 KiB
Go
71 lines
2.7 KiB
Go
package view
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import (
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"crypto/sha256"
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"encoding/hex"
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"io/fs"
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"net/http"
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"path"
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)
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// staticETags maps each /static/ URL path to a strong ETag over the asset's
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// bytes, computed once at startup from the embedded FS.
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//
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// The assets are baked into the binary, so their FS modification times are the
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// zero value and http.FileServer sends no Last-Modified. Without an ETag either,
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// a response carries no validator at all and the browser is free to guess how
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// long to keep it — which is how a replaced favicon keeps showing the old mark
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// long after a deploy. Hashing the content gives every asset a validator that
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// changes exactly when the asset does. RFC 9111 § 4.2.2: without explicit
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// freshness a cache may assign a heuristic lifetime; Go 1.26, net/http fs.go
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// ServeContent(): no Last-Modified for a zero modtime, and an ETag the caller
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// set answers If-None-Match.
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var staticETags = buildStaticETags()
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func buildStaticETags() map[string]string {
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etags := make(map[string]string)
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// An error here would mean the embed directive and this walk disagree, which
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// is a build-time defect rather than a runtime condition; the assets still
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// serve correctly without a validator, so skip what can't be read.
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_ = fs.WalkDir(assetsFS, "static", func(name string, d fs.DirEntry, err error) error {
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if err != nil || d.IsDir() {
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return nil
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}
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b, err := fs.ReadFile(assetsFS, name)
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if err != nil {
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return nil
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}
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sum := sha256.Sum256(b)
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etags["/"+name] = `"` + hex.EncodeToString(sum[:16]) + `"`
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return nil
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})
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return etags
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}
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// StaticHandler serves the embedded assets under /static/ with a content ETag.
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// A path that is not one of those assets — the folder itself included — is a
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// 404: the file server would otherwise answer the folder with a listing of
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// everything the binary embeds.
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//
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// Cache-Control is no-cache rather than a max-age: it lets the browser keep the
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// copy but requires it to revalidate, so an asset that changed is picked up on
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// the next page load while an unchanged one costs a 304 with no body. For a
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// handful of small files on a single-operator panel that trade is the right way
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// round — correctness after a deploy matters more than saving the round trip.
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// http.ServeContent answers the conditional request from the ETag we set here.
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// RFC 9111 § 5.2.2.4: no-cache lets a cache store the response but not reuse
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// it without validating it first.
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func StaticHandler() http.Handler {
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files := http.FileServer(http.FS(assetsFS))
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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etag, ok := staticETags[path.Clean(r.URL.Path)]
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if !ok {
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http.NotFound(w, r)
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return
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}
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w.Header().Set("ETag", etag)
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w.Header().Set("Cache-Control", "no-cache")
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files.ServeHTTP(w, r)
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})
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}
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