diff --git a/docs/sync/README.md b/docs/sync/README.md
index 84558dde..64540b83 100644
--- a/docs/sync/README.md
+++ b/docs/sync/README.md
@@ -120,9 +120,9 @@ A pseudonymous `device_id` distinguishes your machines without revealing hostnam
 | `git.in_main` | `true` | Whether the commit landed in the main branch |
 | `git.was_reverted` | `false` | Whether a later commit reverted it |
 
-Attribution is **inferred** (timestamp-window correlation, the same heuristic as `codeburn yield`); the resource attribute `codeburn.attribution_methodology: timestamp-window` marks it as such. State transitions (a commit merging to main, or being reverted) are re-sent automatically on later pushes — receivers should upsert by `(git.repo, git.sha)`.
+Attribution is **inferred** (timestamp-window correlation, the same heuristic as `codeburn yield`); the resource attribute `codeburn.attribution_methodology: timestamp-window` marks it as such. State transitions (a commit merging to main, or being reverted) are re-sent automatically on later pushes — receivers should upsert commits by `(git.repo, git.sha)` and session spans by `ai.session_id` (latest state wins). When a commit migrates to a later-parsed session with a tighter window, the losing session re-emits with `git.commit_count: 0` (a retraction), so summing `git.commit_count` across upserted session rows never double-counts. Retractions fire only when the commit was won by another session — commits that merely age out of the `--since` window are not retracted, so a previously-synced count stays correct. Session spans also re-emit when an ongoing session's window grows, keeping the span end time current.
 
-With `--attribution`, normalized repo remote URLs, commit SHAs, commit timestamps (span start times), PR URLs, and the merged/reverted booleans leave your machine — plus the same pseudonymous `codeburn.device_id` resource attribute the usage spans carry. PR links are shape-checked client-side (https, `/org/repo/pull/N` path, bounded length, max 20 per session) before sending. Precisely what is and is not sent:
+With `--attribution`, normalized repo remote URLs, commit SHAs, commit timestamps (span start times), PR URLs, and the merged/reverted booleans leave your machine — plus the same pseudonymous `codeburn.device_id` resource attribute the usage spans carry. PR links are rebuilt client-side from scheme + host + path only (userinfo, query strings, and fragments are dropped; https, `/org/repo/pull/N` path, bounded length, max 20 per session), and the repo identity itself passes a strict hostname/path allow-list before sending — malformed or transport-helper remotes (`ext::…`, `codecommit::…`) are rejected outright rather than parsed. Precisely what is and is not sent:
 
 - **Commits**: only from repos with a network `origin` remote, and only for sessions whose own project path resolved to that repo. Local-only repos, `file://` remotes, and Windows filesystem paths are never emitted as repo identities. A session whose project path no longer resolves never inherits the repo of the directory you happen to push from.
 - **PR links**: sent whenever a session captured them, even when the session's repo could not be identified — the PR URL itself names the repo, so this adds no information beyond the link the session already recorded.
diff --git a/src/sync/cli.ts b/src/sync/cli.ts
index a48561c5..f6f28db6 100644
--- a/src/sync/cli.ts
+++ b/src/sync/cli.ts
@@ -371,6 +371,12 @@ export function registerSyncCommands(program: Command): void {
               process.stderr.write('Auth rejected by server during attribution push. Run `codeburn sync setup` to re-authenticate.\n')
               process.exit(1)
             }
+            if (attrResult.outcome === 'rate-limited') {
+              process.stderr.write(`Rate limited during attribution push — gave up after repeated retries. Remaining facts will be sent on the next push.\n`)
+            }
+            if (attrResult.outcome === 'server-error') {
+              process.stderr.write(`Server error (HTTP ${attrResult.httpStatus}) during attribution push. Remaining facts will be sent on the next push.\n`)
+            }
           } else {
             process.stderr.write(`Skipping attribution push (${attributionUnsent.length} facts) — will retry on next push.\n`)
           }
@@ -382,7 +388,10 @@ export function registerSyncCommands(program: Command): void {
         // Summary
         process.stderr.write(`\nSynced ${result.totalSent} calls ($${result.totalCostSent.toFixed(2)}) to ${config.baseUrl}\n`)
         if (attrResult) {
-          process.stderr.write(`  Attribution: ${attrResult.totalSent} facts synced${attrResult.totalRejected > 0 ? `, ${attrResult.totalRejected} rejected (will retry)` : ''}\n`)
+          const attrSuffix = attrResult.outcome !== 'complete'
+            ? ` (push incomplete — remainder retries next push)`
+            : attrResult.totalRejected > 0 ? `, ${attrResult.totalRejected} rejected (will retry)` : ''
+          process.stderr.write(`  Attribution: ${attrResult.totalSent} facts synced${attrSuffix}\n`)
         }
         if (result.totalRejected > 0) {
           process.stderr.write(`  ${result.totalRejected} spans rejected (will retry on next push)\n`)
diff --git a/src/sync/otlp.ts b/src/sync/otlp.ts
index d6a042e0..8df36c59 100644
--- a/src/sync/otlp.ts
+++ b/src/sync/otlp.ts
@@ -189,7 +189,22 @@ export function sessionAttributionKey(record: SessionAttributionRecord): string
   const commitStates = record.commits
     .map(c => `${c.sha}:${c.inMain ? 1 : 0}${c.wasReverted ? 1 : 0}`)
     .sort()
-  return `attr:s:${record.sessionId}:${stateHash([record.repo ?? '', ...record.prLinks, ...commitStates])}`
+  // Project and both window timestamps are part of the state: an ongoing
+  // session whose window grew (or whose project resolution changed) re-emits
+  // with the corrected span times instead of freezing at first send.
+  return `attr:s:${record.sessionId}:${stateHash([
+    record.repo ?? '',
+    record.project,
+    record.firstTimestamp,
+    record.lastTimestamp,
+    ...record.prLinks,
+    ...commitStates,
+  ])}`
+}
+
+/** Ledger-key prefix for a session's attribution facts (any state). */
+export function sessionAttributionKeyPrefix(sessionId: string): string {
+  return `attr:s:${sessionId}:`
 }
 
 /** Flatten attribution records into ledger-able items (one session item + one per commit). */
@@ -234,9 +249,11 @@ export function buildAttributionOtlpPayload(items: AttributionItem[]): OtlpPaylo
 
   const spans: OtlpSpan[] = items.map(item => {
     const startNano = toUnixNano(item.timestamp)
-    const endNano = item.endTimestamp
-      ? toUnixNano(item.endTimestamp)
-      : (BigInt(startNano) + 1_000_000n).toString()
+    // Clamp like the usage builder: end is never 0 (malformed timestamp) and
+    // never earlier than start + 1ms (out-of-order session timestamps).
+    const minEndNano = BigInt(startNano) + 1_000_000n
+    const rawEndNano = item.endTimestamp ? BigInt(toUnixNano(item.endTimestamp)) : 0n
+    const endNano = (rawEndNano > minEndNano ? rawEndNano : minEndNano).toString()
 
     const attributes: OtlpAttribute[] = [
       { key: 'ai.session_id', value: { stringValue: item.sessionId } },
diff --git a/src/sync/push.ts b/src/sync/push.ts
index a0ffc016..7a22420e 100644
--- a/src/sync/push.ts
+++ b/src/sync/push.ts
@@ -209,8 +209,24 @@ export function collectUnsentAttribution(records: SessionAttributionRecord[]): {
   allItems: AttributionItem[]
   unsent: AttributionItem[]
 } {
-  const allItems = flattenAttributionRecords(records)
   const sent = ledgerKeySet()
+
+  // Empty records (no commits, no PR links) exist only to RETRACT a session
+  // span whose commits migrated to another session. Send one only when a
+  // PRIOR state for that session was already ledgered — a session that was
+  // never sent has nothing to retract.
+  const sessionsWithPriorState = new Set<string>()
+  for (const key of sent) {
+    if (key.startsWith('attr:s:')) {
+      const sessionId = key.slice('attr:s:'.length, key.lastIndexOf(':'))
+      sessionsWithPriorState.add(sessionId)
+    }
+  }
+  const sendable = records.filter(r =>
+    r.commits.length > 0 || r.prLinks.length > 0 || sessionsWithPriorState.has(r.sessionId),
+  )
+
+  const allItems = flattenAttributionRecords(sendable)
   const unsent = allItems.filter(i => !sent.has(i.dedupKey))
   return { allItems, unsent }
 }
diff --git a/src/yield.ts b/src/yield.ts
index 33e435af..79239b99 100644
--- a/src/yield.ts
+++ b/src/yield.ts
@@ -146,6 +146,24 @@ function getMainBranch(cwd: string): string {
  * and a trailing `.git` / `/` is removed. Local paths and `file://` remotes
  * return null — a repo with no network remote has no server-side identity.
  */
+/** Max length of an emitted repo identity (`host/org/repo`). */
+const MAX_REPO_IDENTITY_LENGTH = 200
+
+/**
+ * Positive validation (allow-list) of a composed repo identity — the final
+ * gate EVERY branch passes through before anything is returned. The host must
+ * look like a hostname and every path segment like a repo path segment, so no
+ * upstream parsing quirk (transport-helper remotes like `ext::…` or
+ * `codecommit::…`, credentials that survived a malformed URL, oversized
+ * strings) can reach the wire. Rejecting is always safe: an unrecognizable
+ * remote simply has no server-side identity.
+ */
+function isValidRepoIdentity(host: string, segments: string[]): boolean {
+  if (!/^[a-z0-9]([a-z0-9.-]*[a-z0-9])?$/.test(host)) return false
+  if (segments.length === 0) return false
+  return segments.every(s => /^[A-Za-z0-9._~-]+$/.test(s))
+}
+
 export function normalizeRemoteUrl(url: string): string | null {
   const trimmed = url.trim()
   if (!trimmed) return null
@@ -159,12 +177,6 @@ export function normalizeRemoteUrl(url: string): string | null {
   let host: string
   let path: string
 
-  // scp-like syntax: [user@]host:path. Host must be at least 2 chars — a
-  // single-character "host" is a Windows drive-relative path (`C:repo`),
-  // never a real remote host. `@` is excluded from the host class so a
-  // rejected single-char host can't backtrack into `user@C` matching as
-  // host "user@C".
-  const scpLike = /^(?:[^@/]+@)?([^:/\\@]{2,}):(?!\/\/)(.+)$/.exec(trimmed)
   if (/^[a-zA-Z][a-zA-Z0-9+.-]*:\/\//.test(trimmed)) {
     let parsed: URL
     try {
@@ -176,22 +188,34 @@ export function normalizeRemoteUrl(url: string): string | null {
     if (!parsed.hostname) return null
     host = parsed.hostname
     path = parsed.pathname
-  } else if (scpLike) {
-    // scp-like syntax: [user@]host:path — not parseable by URL
+  } else {
+    // scp-like syntax: [user@]host:path. Credentials (userinfo) are split off
+    // at the FIRST `@` BEFORE any host matching — expressing userinfo as an
+    // optional regex group lets backtracking abandon the group and re-parse a
+    // credential prefix as `host:path`, dumping the token into the path
+    // (e.g. `x-access-token:ghp_…@github.com/org/repo`). Host must be at
+    // least 2 chars: a single-character "host" is a Windows drive-relative
+    // path (`C:repo`), never a real remote host.
+    const at = trimmed.indexOf('@')
+    const rest = at >= 0 ? trimmed.slice(at + 1) : trimmed
+    const scpLike = /^([^:/\\]{2,}):(?!\/\/)(.+)$/.exec(rest)
+    if (!scpLike) return null
     host = scpLike[1]
     path = scpLike[2]
-  } else {
-    // Bare local path (or something unrecognizable) — no remote identity.
-    return null
   }
 
   const cleanPath = path
+    .replace(/\/+/g, '/')      // collapse doubled slashes → one join key, not two
     .replace(/^\/+/, '')
     .replace(/\/+$/, '')
-    .replace(/\.git$/, '')
+    .replace(/\.git$/i, '')    // case-insensitive: Repo.GIT joins with repo.git
   if (!cleanPath) return null
 
-  return `${host.toLowerCase()}/${cleanPath}`
+  const identity = `${host.toLowerCase()}/${cleanPath}`
+  if (identity.length > MAX_REPO_IDENTITY_LENGTH) return null
+  if (!isValidRepoIdentity(host.toLowerCase(), cleanPath.split('/'))) return null
+
+  return identity
 }
 
 /** `git remote get-url origin`, normalized. Null when absent or local-only. */
@@ -569,21 +593,6 @@ export type SessionAttributionRecord = {
   lastTimestamp: string
 }
 
-/**
- * Compute per-session attribution records for sync. Reuses the exact yield
- * repo grouping + tightest-window commit attribution (`methodology:
- * timestamp-window`), then joins in each repo group's normalized origin
- * remote and the session's PR links.
- *
- * Inclusion rules:
- * - Sessions with neither attributed commits nor PR links are omitted.
- * - Commits are only included when the repo has a normalized remote; a SHA
- *   without a repo identity has no server-side meaning. Such sessions still
- *   emit a record when they carry PR links (the PR URL embeds the repo).
- *
- * Takes already-parsed projects (sync push has them in hand) instead of
- * re-parsing like computeYield does.
- */
 /** Max PR links retained per session attribution record. */
 export const MAX_PR_LINKS_PER_SESSION = 20
 
@@ -592,11 +601,16 @@ export const MAX_PR_LINKS_PER_SESSION = 20
  * verify truthiness, so arbitrary strings can land in `session.prLinks`.
  * Keep only https URLs shaped like a PR (`/org/repo/pull/N` — GitHub and
  * GitHub Enterprise), bounded in length, capped per session, sorted.
+ *
+ * Links are REBUILT from `origin + pathname`, never passed through verbatim:
+ * userinfo (`https://alice:token@…`), query strings (copy-pasted GitHub
+ * links routinely carry `?notification_referrer_id=…`), and fragments are
+ * all dropped. Rebuilt links that collapse to the same URL dedupe.
  */
 export function sanitizePrLinks(links: string[]): string[] {
-  const valid: string[] = []
+  const valid = new Set<string>()
   for (const link of links) {
-    if (typeof link !== 'string' || link.length === 0 || link.length > 256) continue
+    if (typeof link !== 'string' || link.length === 0 || link.length > 512) continue
     let url: URL
     try {
       url = new URL(link)
@@ -605,11 +619,34 @@ export function sanitizePrLinks(links: string[]): string[] {
     }
     if (url.protocol !== 'https:') continue
     if (!/^\/[^/]+\/[^/]+\/pull\/\d+$/.test(url.pathname)) continue
-    valid.push(link)
+    const rebuilt = `${url.origin}${url.pathname}`
+    if (rebuilt.length > 256) continue
+    valid.add(rebuilt)
   }
-  return valid.sort().slice(0, MAX_PR_LINKS_PER_SESSION)
+  return [...valid].sort().slice(0, MAX_PR_LINKS_PER_SESSION)
 }
 
+/**
+ * Compute per-session attribution records for sync. Reuses the exact yield
+ * repo grouping + tightest-window commit attribution (`methodology:
+ * timestamp-window`), then joins in each repo group's normalized origin
+ * remote and the session's sanitized PR links.
+ *
+ * Inclusion rules:
+ * - Only sessions whose OWN project path resolved to a repo participate in
+ *   commit attribution; cwd-fallback sessions never carry a repo or commits
+ *   (privacy gate — see below) but still emit a record when they have PR links.
+ * - Commits require a normalized remote; a SHA without a repo identity has
+ *   no server-side meaning.
+ * - A session with no commits and no PR links is emitted ONLY when it lost a
+ *   commit to a tighter-window session in THIS computation (`lostCandidacy`)
+ *   — a retraction candidate. A session that merely aged its commits out of
+ *   the range lost them to nobody, and emitting an empty record for it would
+ *   permanently retract a still-correct server-side count.
+ *
+ * Takes already-parsed projects (sync push has them in hand) instead of
+ * re-parsing like computeYield does.
+ */
 export function computeAttributionRecords(
   projects: ProjectSummary[],
   range: DateRange,
@@ -636,8 +673,10 @@ export function computeAttributionRecords(
     // Keyed by object reference: session objects are unique per group entry,
     // whereas sessionId strings could collide across projects.
     const attributionBySession = new Map<SessionSummary, CommitInfo[]>()
+    const lostCandidacyBySession = new Map<SessionSummary, boolean>()
     for (const [i, session] of ownSessions.entries()) {
       attributionBySession.set(session, attributions[i]?.commits ?? [])
+      lostCandidacyBySession.set(session, attributions[i]?.lostCandidacy ?? false)
     }
 
     for (const [index, session] of group.sessions.entries()) {
@@ -649,7 +688,17 @@ export function computeAttributionRecords(
         ? (attributionBySession.get(session) ?? [])
         : []
       const prLinks = sanitizePrLinks(session.prLinks ?? [])
-      if (attributedCommits.length === 0 && prLinks.length === 0) continue
+      // Empty sessions are retraction candidates ONLY when they lost a commit
+      // to a tighter-window session in THIS run: that commit's server-side
+      // attribution is migrating, so the loser must re-emit commit_count=0.
+      // An empty session whose commits merely aged out of the --since range
+      // (rolling window, or a narrower window than a previous push) lost them
+      // to NOBODY — emitting a retraction for it would permanently zero a
+      // still-correct server-side count, because the original state key stays
+      // ledgered and is never re-sent.
+      const lostToTighterSession = sessionRemote !== null &&
+        (lostCandidacyBySession.get(session) ?? false)
+      if (attributedCommits.length === 0 && prLinks.length === 0 && !lostToTighterSession) continue
 
       records.push({
         sessionId: session.sessionId,
diff --git a/tests/sync-attribution.test.ts b/tests/sync-attribution.test.ts
index 4012b4c4..d4b8f6c1 100644
--- a/tests/sync-attribution.test.ts
+++ b/tests/sync-attribution.test.ts
@@ -133,6 +133,40 @@ describe('normalizeRemoteUrl', () => {
     expect(normalizeRemoteUrl('gitserver:team/repo.git')).toBe('gitserver/team/repo')
     expect(normalizeRemoteUrl('git@gitbox:org/repo.git')).toBe('gitbox/org/repo')
   })
+
+  it('never leaks credentials via scp-branch backtracking on malformed remotes', () => {
+    // Credential-prefixed remotes: the userinfo split happens BEFORE host
+    // matching, so a token can never be re-parsed as host:path.
+    expect(normalizeRemoteUrl('x-access-token:ghp_LIVETOKEN_abcdefghijklmnop@github.com/acme/private-repo.git')).toBeNull()
+    expect(normalizeRemoteUrl('oauth2:glpat-TOKEN@gitlab.com/org/repo.git')).toBeNull()
+    // One dropped slash: not a URL, must not fall through as host "https"
+    expect(normalizeRemoteUrl('https:/user:ghp_TOKEN@github.com/org/repo.git')).toBeNull()
+    // Multiple @: split at the first, residual @ fails the allow-list
+    expect(normalizeRemoteUrl('a@b@github.com:org/repo.git')).toBeNull()
+    expect(normalizeRemoteUrl('user@host:path@with-at')).toBeNull()
+  })
+
+  it('rejects transport-helper remotes and enforces shape + length on the identity', () => {
+    // git-remote-ext: embeds a local SSH key path
+    expect(normalizeRemoteUrl('ext::ssh -i /Users/me/.ssh/id_ed25519_work git@github.com %S /acme/private.git')).toBeNull()
+    expect(normalizeRemoteUrl('ext::sh -c whatever')).toBeNull()
+    // git-remote-codecommit: embeds an AWS profile name
+    expect(normalizeRemoteUrl('codecommit::us-east-1://MyAwsProfile@MyRepo')).toBeNull()
+    expect(normalizeRemoteUrl('codecommit::us-east-1://MyRepo')).toBeNull()
+    // Length bound
+    expect(normalizeRemoteUrl(`git@github.com:org/${'a'.repeat(300)}.git`)).toBeNull()
+    // Path segments must be repo-shaped (no spaces, colons, @)
+    expect(normalizeRemoteUrl('gitserver:has space/repo.git')).toBeNull()
+    // Legit multi-segment (GitLab subgroup) paths survive the allow-list
+    expect(normalizeRemoteUrl('https://gitlab.example.com/group/sub/repo.git')).toBe('gitlab.example.com/group/sub/repo')
+  })
+
+  it('normalizes .GIT case-insensitively and collapses doubled slashes to one join key', () => {
+    expect(normalizeRemoteUrl('git@github.com:acme/Repo.GIT')).toBe('github.com/acme/Repo')
+    expect(normalizeRemoteUrl('https://github.com/acme/Repo.Git')).toBe('github.com/acme/Repo')
+    expect(normalizeRemoteUrl('https://github.com/acme//repo.git')).toBe('github.com/acme/repo')
+    expect(normalizeRemoteUrl('git@github.com:acme//repo.git')).toBe('github.com/acme/repo')
+  })
 })
 
 // ── computeAttributionRecords ─────────────────────────────────────────
@@ -172,13 +206,16 @@ describe('computeAttributionRecords', () => {
     }
   })
 
-  it('omits sessions with no commits and no PR links', async () => {
+  it('omits empty sessions that lost nothing — commits aged out of range are NOT retracted', async () => {
     const repoDir = await mkdtemp(join(tmpdir(), 'codeburn-attr-empty-'))
     try {
       initRepo(repoDir)
       git(repoDir, ['remote', 'add', 'origin', 'git@github.com:acme/widget.git'])
       await writeFile(join(repoDir, 'file.txt'), 'hello\n')
-      // Commit outside every session window
+      // Commit outside every session window: no session competes for it, so
+      // nobody "lost" it. Even if this session previously synced a commit
+      // (now outside the --since range), emitting an empty record here would
+      // permanently zero a still-correct server-side count.
       commitAt(repoDir, 'feat: unrelated', '2026-01-01T20:00:00Z')
 
       const session = makeSession({ sessionId: 'sess-idle' })
@@ -187,6 +224,44 @@ describe('computeAttributionRecords', () => {
       ]
 
       expect(computeAttributionRecords(projects, range, repoDir)).toEqual([])
+
+      // …and therefore nothing can be sent, even with prior ledger state for
+      // this session (simulating an earlier wider---since push).
+      const { writeLedger } = await import('../src/sync/ledger.js')
+      writeLedger([{ key: 'attr:s:sess-idle:0123456789abcdef', ts: '2026-01-01T10:00:00.000Z' }])
+      const { collectUnsentAttribution } = await import('../src/sync/push.js')
+      expect(collectUnsentAttribution(computeAttributionRecords(projects, range, repoDir)).unsent).toEqual([])
+    } finally {
+      await rm(repoDir, { recursive: true, force: true })
+    }
+  })
+
+  it('emits a retraction candidate for a session that lost its commit to a tighter window', async () => {
+    const repoDir = await mkdtemp(join(tmpdir(), 'codeburn-attr-lost-'))
+    try {
+      initRepo(repoDir)
+      git(repoDir, ['remote', 'add', 'origin', 'git@github.com:acme/widget.git'])
+      await writeFile(join(repoDir, 'file.txt'), 'hello\n')
+      commitAt(repoDir, 'feat: contested', '2026-01-01T10:30:00Z')
+
+      const tight = makeSession({
+        sessionId: 'sess-tight',
+        firstTimestamp: '2026-01-01T10:15:00.000Z',
+        lastTimestamp: '2026-01-01T10:45:00.000Z',
+      })
+      const broadLoser = makeSession({ sessionId: 'sess-broad-loser' })
+      const projects = [
+        { project: 'app', projectPath: repoDir, sessions: [tight, broadLoser] } as ProjectSummary,
+      ]
+
+      const records = computeAttributionRecords(projects, range, repoDir)
+      const loser = records.find(r => r.sessionId === 'sess-broad-loser')!
+      // The loser IS emitted (retraction candidate: lostCandidacy) with zero
+      // commits — the sync layer decides whether a prior state warrants
+      // actually sending it.
+      expect(loser).toBeDefined()
+      expect(loser.commits).toEqual([])
+      expect(loser.repo).toBe('github.com/acme/widget')
     } finally {
       await rm(repoDir, { recursive: true, force: true })
     }
@@ -326,9 +401,13 @@ describe('computeAttributionRecords', () => {
 
       const records = computeAttributionRecords(projects, range, repoDir)
 
-      expect(records).toHaveLength(1)
-      expect(records[0]!.sessionId).toBe('sess-tight')
-      expect(records[0]!.commits).toHaveLength(1)
+      // Both sessions get records (the loser is a retraction candidate),
+      // but the commit is awarded exactly once — to the tighter window.
+      expect(records).toHaveLength(2)
+      const tightRecord = records.find(r => r.sessionId === 'sess-tight')!
+      const broadRecord = records.find(r => r.sessionId === 'sess-broad')!
+      expect(tightRecord.commits).toHaveLength(1)
+      expect(broadRecord.commits).toEqual([])
     } finally {
       await rm(repoDir, { recursive: true, force: true })
     }
@@ -372,6 +451,14 @@ describe('attribution dedup keys', () => {
     expect(sessionAttributionKey(mutated)).not.toBe(sessionAttributionKey(record))
   })
 
+  it('session key changes when the window or project changes (ongoing sessions re-emit)', () => {
+    const base = makeRecord()
+    const grown = makeRecord({ lastTimestamp: '2026-01-01T12:00:00.000Z' })
+    const renamed = makeRecord({ project: 'app-renamed' })
+    expect(sessionAttributionKey(grown)).not.toBe(sessionAttributionKey(base))
+    expect(sessionAttributionKey(renamed)).not.toBe(sessionAttributionKey(base))
+  })
+
   it('flattens one session item plus one item per commit', () => {
     const items = flattenAttributionRecords([makeRecord()])
     expect(items).toHaveLength(2)
@@ -404,9 +491,36 @@ describe('sanitizePrLinks', () => {
     ])
   })
 
-  it('drops oversized strings and caps the count per session', () => {
-    const huge = `https://github.com/acme/widget/pull/1?x=${'a'.repeat(300)}`
+  it('rebuilds links from origin + pathname: userinfo, query, and fragment never survive', () => {
+    expect(sanitizePrLinks([
+      'https://alice:ghp_TOKEN@github.com/acme/widget/pull/5',
+      'https://github.com/acme/widget/pull/7?notification_referrer_id=xyz',
+      'https://github.com/acme/widget/pull/6#pullrequestreview-123',
+    ])).toEqual([
+      'https://github.com/acme/widget/pull/5',
+      'https://github.com/acme/widget/pull/6',
+      'https://github.com/acme/widget/pull/7',
+    ])
+  })
+
+  it('dedupes links that collapse to the same rebuilt URL', () => {
+    expect(sanitizePrLinks([
+      'https://github.com/acme/widget/pull/9',
+      'https://github.com/acme/widget/pull/9?ref=a',
+      'https://github.com/acme/widget/pull/9#comment',
+    ])).toEqual(['https://github.com/acme/widget/pull/9'])
+  })
+
+  it('drops oversized inputs and caps the count per session', () => {
+    // A long referrer query is stripped, so the link survives...
+    const longQuery = `https://github.com/acme/widget/pull/1?x=${'a'.repeat(300)}`
+    expect(sanitizePrLinks([longQuery])).toEqual(['https://github.com/acme/widget/pull/1'])
+    // ...but pathological inputs beyond the input bound are dropped outright
+    const huge = `https://github.com/acme/widget/pull/1?x=${'a'.repeat(600)}`
     expect(sanitizePrLinks([huge])).toEqual([])
+    // And a rebuilt link that is itself oversized is dropped
+    const longPath = `https://github.com/${'o'.repeat(150)}/${'r'.repeat(80)}/pull/1`
+    expect(sanitizePrLinks([longPath])).toEqual([])
 
     const many = Array.from({ length: 30 }, (_, i) => `https://github.com/acme/widget/pull/${i + 1}`)
     expect(sanitizePrLinks(many)).toHaveLength(MAX_PR_LINKS_PER_SESSION)
@@ -472,6 +586,22 @@ describe('buildAttributionOtlpPayload', () => {
     const items = flattenAttributionRecords([makeRecord(), makeRecord({ sessionId: 'sess-2' })])
     expect(batchAttributionItems(items, 3).map(b => b.length)).toEqual([3, 1])
   })
+
+  it('clamps span end time: never 0, never earlier than start + 1ms', () => {
+    // Session window ends BEFORE it starts (out-of-order provider timestamps)
+    const outOfOrder = flattenAttributionRecords([makeRecord({
+      firstTimestamp: '2026-01-01T11:00:00.000Z',
+      lastTimestamp: '2026-01-01T10:00:00.000Z',
+    })])
+    const span1 = buildAttributionOtlpPayload(outOfOrder).resourceSpans[0]!.scopeSpans[0]!.spans[0]!
+    expect(BigInt(span1.endTimeUnixNano)).toBe(BigInt(span1.startTimeUnixNano) + 1_000_000n)
+
+    // Malformed end timestamp (toUnixNano -> 0)
+    const malformed = flattenAttributionRecords([makeRecord({ lastTimestamp: 'not-a-date' })])
+    const span2 = buildAttributionOtlpPayload(malformed).resourceSpans[0]!.scopeSpans[0]!.spans[0]!
+    expect(span2.endTimeUnixNano).not.toBe('0')
+    expect(BigInt(span2.endTimeUnixNano)).toBe(BigInt(span2.startTimeUnixNano) + 1_000_000n)
+  })
 })
 
 // ── Send + ledger pipeline ────────────────────────────────────────────
@@ -566,6 +696,42 @@ describe('sendAttributionBatches + collectUnsentAttribution', () => {
     }
   })
 
+  it('retracts a session span when its commit migrates to a tighter-window session', async () => {
+    const { sendAttributionBatches, collectUnsentAttribution } = await import('../src/sync/push.js')
+
+    const sha = 'b'.repeat(40)
+    const commit = { sha, timestamp: '2026-01-01T10:30:00.000Z', inMain: true, wasReverted: false }
+
+    // Push 1: session A (broad window) owns the commit
+    const push1 = collectUnsentAttribution([makeRecord({ sessionId: 'sess-A', prLinks: [], commits: [commit] })])
+    expect(push1.unsent).toHaveLength(2)
+    const mock = await startMockOtlp([{ status: 200 }])
+    try {
+      await sendAttributionBatches({ endpoint: mock.url, accessToken: 't', batches: [push1.unsent] })
+
+      // Push 2: a later-parsed tighter session B now wins the commit; A is empty
+      const push2 = collectUnsentAttribution([
+        makeRecord({ sessionId: 'sess-A', prLinks: [], commits: [] }),          // loser: retraction candidate
+        makeRecord({ sessionId: 'sess-B', prLinks: [], commits: [commit] }),    // winner
+      ])
+
+      // A re-emits with commit_count 0 (retraction), B emits session + commit
+      const kinds = push2.unsent.map(i => `${i.sessionId}:${i.kind}`).sort()
+      expect(kinds).toEqual(['sess-A:session', 'sess-B:commit', 'sess-B:session'])
+      const retraction = push2.unsent.find(i => i.sessionId === 'sess-A')!
+      expect(retraction.commitCount).toBe(0)
+      expect(retraction.dedupKey).not.toBe(push1.unsent.find(i => i.kind === 'session')!.dedupKey)
+
+      // A session that was NEVER sent stays excluded when empty
+      const neverSent = collectUnsentAttribution([
+        makeRecord({ sessionId: 'sess-never', prLinks: [], commits: [] }),
+      ])
+      expect(neverSent.unsent).toEqual([])
+    } finally {
+      mock.server.close()
+    }
+  })
+
   it('does not ledger on server error', async () => {
     const { sendAttributionBatches } = await import('../src/sync/push.js')
     const { readLedger } = await import('../src/sync/ledger.js')